15Bit Offline Upload & Sell: Off
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Alan321 wrote:
In the end it was all too complicated
It is rather complicated, especially now that the manufacturers are segmenting their product lines in so many ways.
In short though, the major differences between drives are:
1. Construction - enterprise drives may have higher tolerance components, better motors, higher inertia platters, spindles anchored at both ends, more internal sensors and faster/more processors. Basically, features to improve reliability and reduce and compensate for vibrations in all axes. Enterprise drives will also ship with ECC cache RAM, and plenty of it. Desktop drives will miss a lot of these features, NAS drives will lie between, having some features but not others. For the consumer, the quality of construction will be reflected in the length of the warranty.
2. Firmware - Increasingly, drives come with firmware optimised to an application: Different drive applications come with different mixes of read and write, and different mixes of random vs sequential transfers. The firmware reflects this. So drives aimed at Desktop PC use (enterprise or consumer) may be optimised to give good overall performance for both sustained transfers and random i/o at relatively low queue depths, whilst media drives will have firmware optimised to sustained and stable transfers. NAS and enterprise array drives will come with firmware that works well when there is a lot of data queued to be read/written, gives good interplay between several drives and gives good hotplug and RAID rebuild characteristics. These differences between these might be things as simple as how aggressively a drive pursues a read/write error - on a desktop drive (consumer or enterprise class) you want the drive to try very hard to recover any errors, but on a media streaming drive (or one of the new "surveillance" grade drives") you don't want your live video recording to be interrupted for 30 secs whilst the drive devotes all it's efforts to reading a bad sector and then remapping a spare from it's cache. Same for a drive in an array - a bad sector doesn't matter because the data can be reconstructed quickly from the checksums/mirrored data.
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