Hi, I'm looking to backup my photos and have a short stack of 400GB drives sitting on my desk. I want to take two of them and put them in a mirrored backup system (RAID 1). I am running Mac OS 10.6.
I have heard much praise of the Drobos, but the smallest one they make is $300 for the 4-bay enclosure. I'm not sure whether I want to spend this much money on an enclosure at this point (I do have 4 400gb drives, though). I'm not even sure whether I need that much backup space at the time being.
I know that Mac OSX has a built in software raid function through Disk Utility, so I was looking at two-drive enclosures like these:
The Cavalry seems to be able to do RAID, while the other two run something called JBOD that I am not familiar with. I just want the two drives to show up as separate drives on my computer so I can RAID them internally. Is this possible with any of these? Is there something else I should consider for a mirrored desktop backup? Thanks in advance!
If you just want the drives to show up individually, then JBOD is exactly what you want. Some external enclosures will only function in an enclosure-provided RAID mode; an enclosure listing JBOD (Just a Bunch of Disks) means it can act as a simple dumb enclosure, allowing you do to RAID with software or hardware controller of your choice.
Okay, thanks. That answers my question. My plan now is to either get a firewire JBOD box and do a software RAID, or set up something with rsync (my housemates are all programmers).
NEVER use Raid for backup. It is for high availability and gives no protection from most problems you are trying to avoid by backing up. RAID does nothing to protect against file corruption, fire, theft, etc. It only protects against mechanical failure of the drive. Also the hardware/software RAID controllers can cause their own problems. I previously used RAID 1 and had a drive failure. Dell was able to straighten things out but strongly urged not using RAID for backup. The support person said that I was the only person in his three years of experience who had a successful outcome from a RAID problem!
You do not say how much backup space you need. The only reason to consider arrays is if you cannot get a single drive big enough to fit everything. In that case it simplifies the logistics of managing backups. In my case the size of available drives is currently keeping ahead of my backup needs. I just switched to 2 TB backup drives, which are reasonably cheap. There are some here who have much larger backup requirements. In that case you either have to use arrays to get a single large virtual drive or split your collection into manageable pieces.
I keep a "Live" backup connected to the system that automatically gets copies of new files. That protects against drive failure. I have a second backup that I keep in a safe deposit box (local TD bank that is open 7 days a week for easy access) and swap the live backup with the one in the vault about once a month. I used to keep it in a fireproof safe in the basement.
If you do not have two completely independent backups, you are not protected. If you want to use something like DROBO, you need to buy two.
software RAID generally blows for performance. If you're going to get an enclosure, just get one that has built-in HW RAID 1 support and slap a few drives in it.
And yes, RAID is not really backup. in my setup, I have a multiple disk RAID 1 setup as primary drive and then use another drive in the enclosure as an rsync destination for the RAID. I then also have a USB drive attached so that is a 2nd backup (and offsite-able). So, in all, I have 4 copies of the data.
A while back I had the opportunity to pick up a bunch of external drives.
I've got them set up in 3 groups of four drives. Each set of four is managed as a raid by the SoftRaid software program, and then Carbon copy cloner mirrors one on to the other every night for backup. 3rd one lives off site and is swapped out periodically.
As a raid they are, I think, significantly faster than jbod, and I have the backup covered by mirroring them to another set.
I have used the Mac disk utility for a mirrored RAID for years. A mirror is not a backup per se but it does have its purpose. If one drive fails you can recover pretty quickly from that. The Mac will use the single drive and you are still in business. The only downside is there is no rebuilding of the RAID available. In my mind this is not an issue because if one drive failed the other may be right behind it. So I would replace the drives anyway.
The external RAID solutions are mostly hardware RAIDs and may have some performance gains but for backup is that really an issue? The downside to most hardware RAIDs is that the drives must be the exact same model, size, firmware, etc. The Mac software allows for any drives to be mirrored. The RAID would only be as big as the smallest drive.
If you are creating a backup from your drives why not just use them separately? Set up a routine to back up to one and then to another. I for one am not a huge fan of backup software because the files are hard to get at individually. I prefer a software files sync program. Chrono Sync is excellent for this. Apple's Time Machine is also an excellent backup that allows you to go back in time and recover deleted files and files that you may have changed but want the original version. Ideally Time Machine would like a drive 2 times the drive it is backing up. However that is for maximum amount of time to recover. I have used it with a drive that was the same size as my main drive and it kept several months worth of changes.
I bought a Drobo about a year ago to store my media files and things I want all my computers to access. I had one of the drives fail a few months ago. Just removed it and installed a replacement and 24 hrs later it was back to 100% health. During the rebuild all my files were available and I did not notice any issues using it. I bought it used and it is a 2nd generation Drobo. I have it connected via USB to my AIrport Extreme and it stores media files. Never had a problem playing back movies from it via the WiFi. Some will tell you the performance is slower. Maybe so but for my needs it is fine. For backup it would be more than enough. I am thinking of replacing all my other drives with another Drobo for Time Machine on my 3 Macs.
I also use CrashPlan for offline backup. I find it to be excellent and runs in the background without slowing down the machine or my internet connection. Used to use Mozy and it was horrible. CrashPlan did take a long time to do the first backup but that was 2 machines, 1 with 1TB of data the other with 500GB of data. The 1TB took a month and a half to fully seed. Since it was running in the background and it is my "last resort" backup I did not really mind that it took so long. If you are in a hurry you can seed it with a hard drive.
The confusion that many people have about the various flavors of RAID is what you pointed out. If a drive is cooked, you can usually get back in business quickly but there are may other ways that data can be lost that RAID does not cover. Therefore as a practical matter, data on a RAID array must be considered a single copy of the data.
Although I have no plans to do so, it seems that RAID is best used for your primary working drive, or for those who need a logical drive size larger than hardware currently available. Then have two seperate single drive backups.
PS: Anyone else notice that we seem to be talking to ourselves. OP seems to be MIA
Heheh, sorry about that. I ended up buying a JBOD enclosure (1.4tb) as primary storage for my photos. I'm using a secondary external, usually disconnected from the computer, as a backup. That's 2 copies of my data… I may add another in a form of another drive, but for now I feel pretty comfortable. Thanks!
Two copies of data is not enough. What if there's a glitch while one is being copied to the other ? Both get zapped. Ditto if you've messed up files without realizing it before you back them up.
I can't say enough good things about Synology NAS devices. They work with Apple and support time machine, and windows. They can use random disk sizes. Check into them.
Unless you really know how to manage a RAID system, and are ready for headaches, I really don't think RAID/JBOD data setups should be used. It's not really worth it.
I've read Spencers article previously. A lot of good information there.
I spent years working with servers in a data centre environment. RAID is used for high availability and for performance. It has absolutely nothing to do with backups. Backups are an entirely different issue.
RAID and Backups are two separate beasts. They have nothing to do with each other.
sboerup wrote:
Unless you really know how to manage a RAID system, and are ready for headaches, I really don't think RAID/JBOD data setups should be used. It's not really worth it.
