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Archive 2016 · Which iMac GPU for Lightroom

  
 
15Bit
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p.3 #1 · p.3 #1 · Which iMac GPU for Lightroom


Certainly in the Apple world your choices are a bit more limited than one might like. And in truth the 2TB Fusion with 128GB probably isn't a bad choice, though the 1TB version with 24GB is in my view a very poor option.

The difficulty is that to get comparable performance from an external you really need to get a thunderbolt enclosure of some sort, and that is costly. But a suggestion could be something like:

Pay $100 for the Apple 256GB SSD upgrade, plus $245 for a dual channel thunderbolt drive dock (http://eshop.macsales.com/item/OWC/TB2U3DKR2/). Another $120 gets you a decent 4TB spinning drive to put in it.

That's going to be around $500 with postage. For your $300 extra over the 2TB fusion option you get twice the SSD storage in the computer and twice the overall storage capacity. You also gain a lot of flexibility with respect to being able to buy more hard disks for backups etc and plug them into the dock.

In terms of workflow, I tend to house all my photos on a NAS, but move the ones i am working on to an SSD on my local computer whilst i am working on them. When finished i move them back to the NAS. You could do similar with the internal 256GB SSD and external spinning drive, or you could purchase an additional SSD to use as the scratch/working drive ($90 for a 250GB samsung 750) and plug that into the second port on the dock.

In truth my major concern with the Fusion is reliability - because it is 2 discrete drives which are formatted together into a single logical volume, the failure of either component will lose everything. And there being two discrete drives, the chance of failure is increased. I have also found SSD's to be somewhat more reliable than spining drives, so i personally view the spinning drive component of the Fusion as a weak link that i would prefer to avoid on the system drive (because even if my data files are backed up, reinstalling everything is a pain in the a**e).



Apr 29, 2016 at 03:26 PM
Ian.Dobinson
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p.3 #2 · p.3 #2 · Which iMac GPU for Lightroom


Jeff : the speed of the Fusion drive is very hard to quantify .

if I run black magic on my late 2012 i get speeds of around 200-250 read and write . when I would think i would see 500-600 for the SSD alone .

but then looking at youtube Ive seen speed tests on the later retina imac's clock 600 ish for the fusion and north of 1000 for the SSD .

but like I said its very hard to quantify the real world speeds due to things be so dynamic . (like I said before ive not been unhappy with my fusion, its just if I was to choose now id go the SSD route as a no cost option)

and yes I get what your saying about your main files not sturating the SSD but I find that if I have a good size preview file for Lightroom and a bunch of smart previews (i use these alot on my Air) I can have a lightroom folder (not including images) over 60gb . how much of that lives in the SSD god knows .

the other thing I will say again is dont get so het up on the speed of externals . unless you shoving around huge video files or larg amounts of data on a regular basis the normal USB 3 speeds are fine . ive used 3 differnt USB 3 drives for my lightroom files . 2 bus powered ones which were between about 50 and 90 mbps and a Mybook Studio which is above 150mbps and in truth in lightroom I really couldnt tell the difference . in fact ive stopped putting my new imports on the fusion drive and just send them straight to an external because I see no difference .

try it to begin with and then if at a later date you feel the need to upgrade to a raided thunderbolt then you have the opportunity .



Apr 29, 2016 at 04:11 PM
Jeff Nolten
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p.3 #3 · p.3 #3 · Which iMac GPU for Lightroom


15Bit, I agree with most of your logic. The 256 GB SSD is a no cost trade for the 2T FD. $200 more gets me a 512 GB SSD. $700 gets me a 1TB SSD. This last is the most attractive alternative because I'm currently using about 600 GB of my 1TB internal HD and have my LR raw file library (about 500 GB) on a 3TB external firewire HD (actually two raided) that is partitioned to also house my time machine backups. I'm getting a thunderbolt to firewire cable. Thus no additional external HDs at this time.

I've read that Lightroom only reads the original RAW file to make several preview sizes. I have LR configured to keep these previews around for a month before deletion. These live in the same folder as the LR catalog which in any SSD scenario should reside on the SSD if I'm actively working LR. The LR application itself should also reside on the SSD in either SSD configuration. LR, PS, and Word are the only apps that seem to take a while to load. Word is almost always active.

So considering this is a 5 year investment do I want to spend yet another $700? I don't think the 512 GB SSD option is big enough not to require new external HDs and that would take me up to $500 anyway. I wish I knew if I could drop the $500 for the upgraded CPU and GPU but haven't found sound answers there either. I'm still not convinced how any of these configuration investments would yield noticeably better performance. I have a range of options between $2500 and $3700. It all seems a crap shoot to me. Ya pays your money and ya takes your chances.

Edit: Hi Ian, yes the current iMacs have the fastest I/O ports for the fusion SSD which wasn't true when SSD first came out. My Lightroom previews folder is running about 15 GB but preview size is dependent on display size so that would go larger perhaps much larger.

Like you said all this is very hard to quantify. The only upgrade I feel confident about is going i7 since that buys base clock speed if nothing else. LR is a CPU hog. Adobe says LR can use up to 6 cores and the i7 appears to have 8 to applications while the i5 doesn't. How much difference this makes is anyone's guess. There are still only 4 cores and there would have to be some serious pipelining going on. Adobe says LR can benefit from having as much as 20 GB cache so going to 32 GB ram seems worth the extra $200. All other upgrades seem pure speculation.



Apr 29, 2016 at 04:17 PM
15Bit
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p.3 #4 · p.3 #4 · Which iMac GPU for Lightroom


Jeff Nolten wrote:
Like you said all this is very hard to quantify. The only upgrade I feel confident about is going i7 since that buys base clock speed if nothing else. LR is a CPU hog. Adobe says LR can use up to 6 cores and the i7 appears to have 8 to applications while the i5 doesn't. How much difference this makes is anyone's guess. There are still only 4 cores and there would have to be some serious pipelining going on. Adobe says LR can benefit from having as much as 20 GB cache so going to 32 GB
...Show more

It's not really 8 cores - it's 4 plus something that intel calls a "hyperthreading core". Hyperthreading adds a little extra hardware to each core to allow it to perform more operations in parallel where the exectution units are free. Basically it is a way of utilising the available hardware more efficiently. It presents to the operating system as a second logical core so that the OS can queue up work as a separate thread, but it isn't actually a second core at all - there are no extra execution units, just queuing hardware. So even though there are 8 cores listed, there are really only 4 doing the work.

For some applications hyperthreading can make a significant performance boost: file compression, video transcoding, rendering seem to benefit well. LR doesn't appear to make much use of the hyperthreading cores though, so an i7 isn't really a great improvement over an i5 at the same clockspeed. As you have noticed though, in the Apple world the upgrade to the 4GHz i7 *is* worthwhile, because it is the only way to get over 3.3GHz. A note on that though - due to the way the turbo functions work on intel CPU's, that 3.3GHz CPU actually runs all 4 cores at 3.6GHz, compared to the 4GHz for the i7, but even with that the i7 represents a >10% performance increase which LR will make good use of. Certainly you would be better off putting money into the CPU than the GPU if that trade-off has to be made.

With respect to the SSD choice it seems your Apple options are a 256GB plus externals or a 1TB. The 512GB is obviously a bad compromise for your usage pattern. I would note that for $600 you can get that dock i mentioned before and a 1TB Samsung 850 EVO SSD to put in it.



Apr 30, 2016 at 01:56 AM
Alan321
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p.3 #5 · p.3 #5 · Which iMac GPU for Lightroom


Jeff Nolten wrote:
I've read that Lightroom only reads the original RAW file to make several preview sizes. I have LR configured to keep these previews around for a month before deletion. These live in the same folder as the LR catalog which in any SSD scenario should reside on the SSD if I'm actively working LR. The LR application itself should also reside on the SSD in either SSD configuration. LR, PS, and Word are the only apps that seem to take a while to load. Word is almost always active.


Lr reads the raw files to make previews when images are first imported or when required. It also reads the raw files if a partially converted version is not already available in the ACR cache - every time you edit or even just look at an image in the develop module. Having images in the Lr preview cache speeds up initial image presentation in the Library module but not so much in the Develop module. Having the image partially processed in the ACR cache speeds up image presentation in the Develop module and also when you do edits in the Library module.

I keep the ACR cache and the Lr preview cache on a speedy drive.

So considering this is a 5 year investment do I want to spend yet another $700? I don't think the 512 GB SSD option is big enough not to require new external HDs and that would take me up to $500 anyway. I wish I knew if I could drop the $500 for the upgraded CPU and GPU but haven't found sound answers there either. I'm still not convinced how any of these configuration investments would yield noticeably better performance. I have a range of options between $2500 and $3700. It all seems a crap shoot to me. Ya pays your...Show more

You are not utilising the potential of Thunderbolt and therefore having the ACR and Lr preview caches on an internal SSD with the Lr catalog database will speed things up. The SSD is likely a very speedy one - way faster than standard SATA drive ports allow - and so you'll see even more benefit.

Lr loves a faster CPU for everything it does - especially file processing that seems not to use multiple CPU cores.

Lr only directly uses the GPU processor for raw file conversions, and that isn't done more than once unless you run out of ACR cache. Furhermore, the benefit of using the GPU can be overcome by the additional data transfers between it and the CPU unless you have a good CPU-GPU link as well as a speedy GPU. On a recent Mac you'll probably come out in front but the real gains will be years away when Lr and Ps make greater use of the GPU. However, if you have a big screen and big image files then moving images around on-screen and especially resizing them or changing their shape will benefit from a graphics system that can quickly update the screen, so you would not want bottom end performance.

Edit: Hi Ian, yes the current iMacs have the fastest I/O ports for the fusion SSD which wasn't true when SSD first came out. My Lightroom previews folder is running about 15 GB but preview size is dependent on display size so that would go larger perhaps much larger.

Previews are generally made large enough to fit the image on the screen but you'll gain more benefit by having full size previews which are not dependent on screen size. With a 1TB SSD you'll still have enough room for 1:1 previews until your library grows significantly bigger than it is already. That day will come eventually, but if it sneaks up on you too quickly you will have the option of attaching another SSD via thunderbolt. Even for a SATA SSD you'll get maximum performance from it on a thunderbolt port.

Like you said all this is very hard to quantify. The only upgrade I feel confident about is going i7 since that buys base clock speed if nothing else. LR is a CPU hog. Adobe says LR can use up to 6 cores and the i7 appears to have 8 to applications while the i5 doesn't. How much difference this makes is anyone's guess. There are still only 4 cores and there would have to be some serious pipelining going on. Adobe says LR can benefit from having as much as 20 GB cache so going to 32 GB ram seems...Show more

Lr is not a CPU hog - but it does love GHz. The more GHz you give it the faster it will go in everything it does. Some things use extra cores but I don't ever see it maxing out my i7. I have seen reports that Lr and Ps do not scale well with additional CPU cores, so you would not bother with an 8-core CPU that has lower GHz. Check out www.macperformanceguide.com

I've had Lr plod along at times without fully utilising the GHz or capacity of the CPU, the RAM, or even the storage transfer capability. It makes me wonder what the hold up is, and I suspect that some CPU instructions are trashing the CPU pipeline to slow things down without fully loading the CPU. Gone are the days when a programmer could know in advance how long any instruction would take to execute, and would be able to optimise the code extremely well. Today the instructions can interfere with each other in ways that you won't know about because you won't know exactly when separate threads are being run; they can pop up anytime.

32GB RAM can be very nice for Ps particularly with large or complex multi-layered edits but is surely a waste for Lr. Lr practically never goes over 6 or 8 GB in my 32GB computer but I will soon try a Windows registry change to make it use a different Windows caching method more akin to a Server than a Workstation. My Lr preview cache is way bigger than 8GB and so if Lr was caching it properly it would use more of the available RAM than it does. The ACR cache is far smaller than it used to be in early versions of Lr and I can't be sure how it's being handled in RAM.

The thing is to not confuse Lr caching (apparently mostly via pre-processed files to reduce processing) with operating system caching (predominantly in RAM to minimise slower file access). I've read that OS X will even cache a RAM disk as if that would be helpful

- Alan



Apr 30, 2016 at 09:26 AM
Jeff Nolten
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p.3 #6 · p.3 #6 · Which iMac GPU for Lightroom


Thanks guys for the detailed explanations. Its good to have an idea of how all the pieces fit together. And how to optimize LR and PS. I also like 15Bit's external SSD drive idea as a future upgrade. A big advantage of SSDs is that they eliminate the head seek time a spinning drive has so random access to a large library of e.g. raw files should be much faster in addition to the faster reads. I could even move the LR catalog and related folders there on a permanent basis.

In the mean time, for this purchase, I can keep my system cost to around $3G, upgrading the CPU and GPU which would be expensive to do later and give the Mac OS fusion SW a chance to prove itself. According to my calculations the OS and everything I'd be working with should fit in 128 GB. There might be some lags, say loading PS after a month of non-use. I'm not really frustrated with the performance I'm seeing now, my main concern is not downgrading performance by going to a 15 MP display. If I get spoiled by seeing fusion SSD performance but its just not enough, replacing the internal disks should be cheaper than processor boards knowing that a technician will have to do it. I feel fairly confident it won't come to that. I'm retired and photography is my hobby. I don't need the system a production graphics designer would need.

Thanks guys for helping me think this through. I appreciate your input even if I've resisted going all SSD.



Apr 30, 2016 at 10:23 AM
Jeff Nolten
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p.3 #7 · p.3 #7 · Which iMac GPU for Lightroom


15Bit or anyone, although this is OT, your explanation of multiple cores, hyper threading, and turbocharging has piqued my curiosity. I'm a retired SW engineer who last saw active duty back in the PowerPC days. One of my last jobs was implementing some Fourier related transforms on large batches of time series data. Each PowerPC core had 4 array processors that could do single precision transcendental math functions. Apple had implemented standard UNIX math libraries to utilize the array processors so that every clock cycle all 8 or 16 processors could do a multiply or other operation. The system was pipelined so the fetch and store operations occurred simultaneously. Once set up data would move through the system very quickly. The math libraries took care of the organization, I just did math function calls. I got orders of magnitude better performance than using Matlab at the time. One of the reasons I am loyal to Apple is because this functionality was freely available and well documented in their developer libraries. Nothing similar was available on the windows or linux systems we were using at the time.

I don't know how Intel implements its cores in a multi core CPU chip but I assume that hyper threading is some sort of pipelining operation, as is turbo boosting perhaps with some clock management. A 4 GHz CPU has a fair amount of spare time compared to its surrounding 1.8 GHz ram. Is this a correct assumption? Also, if hyper threading makes 4 cores appear as 8 to the OS, how would LR know it didn't have 6 available cores and choose to use less because they weren't real? I understand how a computer works but all this plumbing is too complicated to keep up with. Thanks if you'd care to explain further.



Apr 30, 2016 at 10:46 AM
Alan321
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p.3 #8 · p.3 #8 · Which iMac GPU for Lightroom


I just recalled that in the early days of Fusion drives they were a big con. Once the SSD part filled up the performance plummeted but few tests at the time revealed that problem. I don't know how that has changed since then.

I worked on the basis that if it was caching the most used files then they would not influence Lr much because I am using too many different files that collectively were heaps bigger than the SSD in the Fusion drive.

I did find that I liked proper SSDs and I paid a high price for that, largely through device failures. Nowadays they can be much faster and much bigger and yet also much cheaper. They're still more expensive than spinning discs but the cost penalty is far more affordable now and the performance difference far greater.

Will you have the chance to upgrade the super fast internal PCIe SSD later on, or are you stuck with the first choice for the life of the computer ?

One saving grace is that thunderbolt 3 will allow use of external PCIe cards including SSDs and even graphics cards - if Apple lets it happen. So far the external graphics have not been possible but tb 3 is expected to change that via the USB 3c cable. I don't know how it will actually be implemented but it looks promising.

My first tb computer only had one port and that was only tb 1. It screamed along when some cases and drives were finally available for it after a year or so and I upgraded to a newer OS X. I would not go back to plain old SATA drives happily.


Jeff, about that 4GHz CPU and its spare time... A fully utilised CPU will have many instructions in different states of execution at any time. I doubt that it would have much spare time if the rest of the system was keeping it fed with data to crunch and if the particular instructions did not involve emptying the instruction queue. As far as I know it is the CPU that determines which cores are used. It can change its mind according to what is coming up and also according to how hot the CPU cores are getting. I'm sure but not certain that Lr will not be able to specify which core is used but will be able to specify how many can be used. Some software that I use lets me limit the number of CPU cores that it uses so that other programs have a chance to run without too much competition. That keeps the interface nice and fluid. Unfortunately, for whatever reason, Adobe limits most disk activity to a single CPU core. There's no universally good reason for this because with other programs that do it you can run multiple instances of the program to get things done faster pretty much in proportion to how many instances you run. This was standard practice with Canon DPP, for instance - e.g. run DPP three times with each one processing a third of the files. So why can't the programs just split the load internally and let the computer figure out how to let it happen efficiently via caching, core selection, RAM management, etc. Make it a user-selectable option just in case it bogs down on old hardware. Should be easy.

- Alan



Apr 30, 2016 at 11:56 AM
15Bit
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p.3 #9 · p.3 #9 · Which iMac GPU for Lightroom


Jeff,

I remember the old Power PC's with vector pre-processors. They were really fast for anything that could utilise them. Unfortunately not all that much could, and the rest of the CPU wasn't all that great compared to Intel's offerings.

Hyperthreading is probably best explained via a quick google search on your part - you'll get a better explanation than i can give. As for LR knowing whether it is seeing "real" or HT cores, the OS will know - the CPU has to present a list of capabilities like MMX etc. for the OS to work correctly, and it needs to know about Hyperthreading in order to schedule tasks efficiently. LR will be able to ask about those capabilities and at the very limit the number of threads it runs to the number of real cores available. I wouldn't be surprised if there is a "no-hyperthreading cores" flag that it can send to the OS too, as HT has been found in the past to slow some things down rather than speed them up. But as the OS deals with thread scheduling, this will ultimately be controlled by it rather than LR.

The turbo is easy to explain - the CPU simply overclocks itself to different degrees depending on the thermal overhead it has available and the number of cores being requested. So for that 3.3GHz i5, if only loading 1 core it will spin up to 3.9Ghz if it can. If using 2 cores it goes to 3.8Ghz, for 3 cores it does 3.7Ghz and for all 4 cores it will try to sustain 3.6Ghz if the thermals allow.

For the i7 4Ghz things are slightly different. Because it is actually already at it's thermal ceiling, it will only spin up to 4.2Ghz for a single core. If more than one core is loaded it stays are 4Ghz.

Personally i think the current clockspeed labelling is very confusing, and given that some CPU's can run all cores at higher than the quoted clockspeed, it may be actively misleading. Indeed, if you look very closely at the intel CPU specs you can turn up anomalies where one CPU is listed as being faster than the one below it in the model range, but actually runs at the same speed if you account for the turbo overclocks.



Apr 30, 2016 at 12:03 PM
Jeff Nolten
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p.3 #10 · p.3 #10 · Which iMac GPU for Lightroom


Thanks for the further explanations. As I suspected, lots of pluming and regulation going on that we have no control over. At least the turbo boost thing is understandably straight forward. Drive the car faster until it overheats. As suggested, I did a quick Google of HT, the gist to me is there are a variety of various compute units that comprise a core, much like the array processors in the PowerPC. These can perform a variety of simultaneous operations but often remain idle when following a single instruction thread or program. Hyper threading allows it to follow two threads to more fully utilize resources as long as prioritization doesn't become too complicated. Sort of taking pipelining to the next level.

I was very happy when I traded my PPC tower for the all in one iMac. Much quieter and more compact. I'm glad I'm retired and a simple user and don't have to worry about all those guys running around in there ala Tron. Just leave me a terminal window so I can run the occasional Perl script now and again.

Alan, I read your rant in the other thread and the Apple Core Rot you referred to. All I can say is after fighting upgrades for 45 years, the more things change the more they stay the same. I've never been certain all this technology upgrade has really helped us. At least it kept me employed. There is never enough time to do it right, but there is always enough time to do it again.

15Bit, I visited Trondheim a couple of times back in the 80s when I was doing oceanography with Scripps Institution. Stunningly beautiful place. I'd love to get back there some time with my current cameras.

Thanks again and Cheers!



Apr 30, 2016 at 01:15 PM
ggreene
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p.3 #11 · p.3 #11 · Which iMac GPU for Lightroom


I have a higher end Mac Pro cylinder and LR is still quite slow on it. It doesn't seem to be very optimized on the Mac side. Even when I ran it on a higher end PC it was slow.

The Library module is particularly bad. It can't cull photos to save it's life. Moving photos around on the flash drive takes way too long. Generating JPEG's takes too long. A lot of the Developer brushes lag badly. It seems to need a major rewrite of the code but I'm not a programmer so I have no idea if that is a viable solution.



Apr 30, 2016 at 05:21 PM
Ian.Dobinson
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p.3 #12 · p.3 #12 · Which iMac GPU for Lightroom


ggreene wrote:
I have a higher end Mac Pro cylinder and LR is still quite slow on it. It doesn't seem to be very optimized on the Mac side. Even when I ran it on a higher end PC it was slow.


I think its probably better optimised on the mac side than the PC side . for one thing menus on hi res screens on the PC side have been bad (must say this may have improved but its a while since I've used LR on a PC.
also there are plenty more stories of LR not working well with X GPU where its fine with Y cpu over on the PC side .



The Library module is particularly bad. It can't cull photos to save it's life.

Sorry I just don't get this . I can cull plenty fast on both my iMac and my macbook air . in fact every machine I've run LR on has had no problems culling . you just have to set things up right in the first place .
have LR create 1:1 previews for the stuff you want to cull . you don't have to wait for it to finish all of your images but its advisable to let it get well enough ahead of where you are going to start culling . (make a cup of coffee/tea and come back when ready )
I set LR to filter only flagged images so that hitting X (reject) or P (pick) automatically sends you to the next image (you can also just use capital X or P but I find the filter works better for me .
I hit F to go full screen and then I just pick or reject all may images I'm culling . I never have to wait for an image trendier (as the 1:1 preview is already built) and can flick between 1:1 and normal view with ease .

I honestly can't see why I need anything to work faster than LR does this as I do have to actually see the images I'm culling and asses them . and on my first culling run the choice is normally as simple as in/out of focus and if its not totally a crap shot .


Moving photos around on the flash drive takes way too long. Generating JPEG's takes too long. A lot of the Developer brushes lag badly. It seems to need a major rewrite of the code but I'm not a programmer so I have no idea if that is a viable solution.


I agree that moving lots of files around in LR can be a slower process . what I do is if moving a lot of files I move them in finder and then point LR at the folder they've moved to when they are done. while its not best practice to do this its also fine if you point LR at the files as soon as they have been moved .



May 01, 2016 at 03:23 AM
15Bit
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p.3 #13 · p.3 #13 · Which iMac GPU for Lightroom


Though it might seem slightly anti-intuitive, i would actually expect LR to run faster on a 4GHz iMac than on the 6 core (or more) Mac Pro.

On paper the hex core should be faster - raw power being 6*3500 = 21000 MHz vs 4*4000 = 16000 Mhz

The problem comes in the differences between how LR scales with CPU MHz and CPU core count. With clockspeed it scales well, close to 1:1. So if you double the CPU MHz you would expect to see close to double the performance. BUT, if you double the core count you will see only around 2.2x speed increase (in my testing on LR4). Take into account that scaling difference and it is easy to see how the hex core might not be the best option.

And before everyone kicks off on an Adobe-bashing tirade - that sort of scaling with core count is not at all unusual for problems which are not intrinsically parallel.



May 01, 2016 at 03:57 AM
OntheRez
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p.3 #14 · p.3 #14 · Which iMac GPU for Lightroom


Jeff,
SSD > platter. Any way you measure it. This is a newer technology that way out-classes the older one. I can't imagine anyone offering you advice here that would disagree with this. The Apple fusion drive uses the SSD that's married to a standard (7200 rpm I believe) 2TB platter. The SSD part is really a (very) sophisticated pre-fetch cache. It is faster than just a plain platter. It is nowhere near as fast as a real SSD. Again, this comes from my comparing a current 27" i7, 32GB RAM, 512 SSD, 4GB GPU with my partner's nearly identical iMac with the fusion drive. Only difference is the "lesser" CPU. Lr pulls files, saves, and executes significantly faster. Hands down.

You mention using the 2TB fusion drive to hold all you pix, but I gather you back up to external drives thus not you don't loses much if the main drive goes TU. As you note platter drives are proven, reliable, and inexpensive (now). In 25+ years I don't think I've seen more than a half dozen truly fail. (This ignores IBM's CMS drive disaster some years back.)

So is it cost effective? Like I said earlier, I'm sure the fusion drive will work fine, and you'll like the improved performance. However, if you've never directly experienced just how much faster the SSD is then you don't really have a reference for your cost/benefit analysis. SSD tech isn't new and is well proven. Think about it. No moving parts. No moving parts. You obviously have some engineering back ground and we all know the more parts in motion, the greater likelihood of failure.

OWC has a nice USB-3 case that will take up to 4 drives. (I think they have a cheaper 2 drive model.) Last drives I bought were Toshiba "enterprise" rated 2TB drives. They were $54@. Thus you can build an external use and/or backup system for far less than you've calculated.

Which is right for you? Shrug. Obviously your call, but I'll never buy another main drive that is not SSD and I'll keep the TB RAID 0 pair as first line storage.

Robert



May 01, 2016 at 10:36 AM
Ian.Dobinson
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p.3 #15 · p.3 #15 · Which iMac GPU for Lightroom


OK to put things in perspective as far as drive speeds go .

hunting around on youtube for speed tests

3tb fusion on a late 2014 i7 iMac gets over 600mbps write and over 700 read . which is faster than my mid 2103 macbook air ssd can get .

but then there is a comment in the comments section for the video that says a late 2015 with 512 SSD gets 1400 write and 1800 read .

https://youtu.be/NXMe2z2EAiU


as I mentioned earlier my late 2012 1tb fusion gets just over 200mbps .


here's a late 2015 with SSD

https://youtu.be/sl_sJIv2J8Y



May 01, 2016 at 11:23 AM
Jeff Nolten
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p.3 #16 · p.3 #16 · Which iMac GPU for Lightroom


Thank you Robert. I agree with everything you've said. In the end I have a budget I don't really want to bust. If I could have gotten a 2 TB fast interface internal SSD for an extra grand I would have had a very hard decision. I don't fit in 1 TB any more and my raw file library is only going to grow.

My current iMac is 2011 vintage, so 5 years old. I'm sure that my next iMac, whenever that is, will not be available with magnetic drives but there will be some other technology option that will be expensive but must have. For me, for this cycle, its the 5K retina display with the P3 color gamut that is driving this upgrade. I'm gambling that my photos won't ever look significantly better on a 27" display than this one. My retina iPad was a revolution in this regard. I have 22 and 24 MP cameras that each out resolve this 15 MP display with comfortable cropping room. A 5D4 is around the corner and 5DS is available. I'm hoping that I won't feel the need to upgrade my 5D3 because I'll see no real image quality gain. (Lets leave DR arguments for later thank you very much. ) Anyway, I wouldn't have upgraded my 2011 machine if it weren't for the new display. I should see performance improvement but that was not my primary upgrade motivation.

I appreciate everyone's input because I'm certainly aware of the tradeoffs in this decision. My LR experience would be better on my current machine just from the tips I've learned. But, as I've said, I'm retired (best job I've ever had!) and ultimate production efficiency is not as critical as it is to many of you.



May 01, 2016 at 12:04 PM
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p.3 #17 · p.3 #17 · Which iMac GPU for Lightroom


To be honest guys, the SSD numbers are now so high that they are largely irrelevant - it was always the latency that gave SSD's that great "fast" feeling, not the transfer rate. And for LR, which is reading image files that are maybe 20-40MB in size, the difference between 500 and 700MB/sec is not a lot. Certainly it's a fraction of the CPU render time.

As for SSD RAID. Well it posts nice sequential transfer numbers but it has little or no real world impact. For some tasks it might even be slower.



May 01, 2016 at 12:09 PM
Jeff Nolten
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p.3 #18 · p.3 #18 · Which iMac GPU for Lightroom


One thing I will be watching is the cost of 1TB external thunderbolt SSDs. They are currently about $600. Moving all my raw and jpeg image files there would certainly offload the fusion software from managing a lot of truly randomly accessed data files. The new machine has two thunderbolt ports so this wouldn't conflict with my time machine drives. Maybe I'll feel I can afford this later in the year.


May 01, 2016 at 01:07 PM
Alan321
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p.3 #19 · p.3 #19 · Which iMac GPU for Lightroom


Samsung does a couple of 2TB SATA SSDs. The only reason I didn't buy one is that before long I will have a tower PC instead of a laptop, and I'll then be wanting a PCIe SSD instead. Luckily, my Windows laptop computer can take two SSDs and I'm getting by with 1TB each.

SSDs are better at reading than writing, because they cannot write single data clusters unless the space has already been cleared and they clear the space in much bigger chunks than single clusters. That is what TRIM is for. The good news is that for storing photos they are perfect - you write the photos in once and then only ever read them after that so long as you have Lr set to not write XMP data to the files - i.e. keep it all in the Lr catalog database.

SSDs or any fast drive system are also great when you want to do bulk data copies to backups. I often used Carbon Copy Cloner to clone entire volumes and it could get the job done very quickly with SSD and thunderbolt. The quicker it gets done the sooner I can separate the backups from the computer to keep them safe.

If you want to stick with HDDs then you can buy a larger capacitty than you think you'll need and split the drive so that you use only the first 1/3 to 2/3 of it for common tasks. There'll be fewer track seeks when doing sustained data transfers and the overall speed is increased. The outermost tracks are roughly twice as fast as the inner most tracks. e.g. Some HDDs can do 200MB/s on the outer tracks and only about 100-110MB/s on the inner tracks. Middle tracks will deliver about 160MB/s. A drive half as big might have speed varying from 190MB/s down to 90MB/s. Older drives are all slower. It's a relatively cheap way to get better performance from single HDDs where you cannot benefit from RAID striping.


For CPUs my relatively recent Windows computers will do some degree of turbo acceleration so long as not all cores are fully busy all of the time. My 2011 i7 MBP would only accelerate the CPU if I manually restricted the CPU to run on two cores or one core instead of 4, and to do that I had to to download the Apple's huge X compiler and use a small utility within X. When I did that the CPU frequency went up and the speed of importing new raw files into Lr went up by the same amount. In Windows, Lr imports use mainly one CPU core and so the CPU got a decent turbo boost without me fiddling with any settings. However, I don't know whether the difference between the two systems was due to the operating systems or the age of the CPUs. Both CPUs had Turbo Boost version 2.0. I don't think I got past the Mavericks OS before abandoning Apple, and the latest OS X may or may not work better. If it behaves as it used to then you will do better to buy a CPU with faster unboosted speed and not rely on turbo boost. Then again, for other tasks Lr and other software can use more than one core, so you'll have to figure out the optimum balance.

- Alan



May 02, 2016 at 10:44 PM
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p.3 #20 · p.3 #20 · Which iMac GPU for Lightroom


well that brings up the question of how much LR benefits as the number of cores increases...


May 02, 2016 at 11:03 PM
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