Re: raid levels and NAS drives

["Austin S. Hemmelgarn" <ahferroin7@gmail.com>]

On 2016-10-11 18:10, Nicholas D Steeves wrote:
> On Mon, Oct 10, 2016 at 08:07:53AM -0400, Austin S. Hemmelgarn wrote:
>> On 2016-10-09 19:12, Charles Zeitler wrote:
>>> Is there any advantage to using NAS drives
>>> under RAID levels,  as oppposed to regular
>>> 'desktop' drives for BTRFS?
> [...]
>> So, as for what you should use in a RAID array, here's my specific advice:
>> 1. Don't worry about enterprise drives unless you've already got a system
>> that has them.  They're insanely overpriced for relatively minimal benefit
>> when compared to NAS drives.
>> 2. If you can afford NAS drives, use them, they'll get you the best
>> combination of energy efficiency, performance, and error recovery.
>> 3. If you can't get NAS drives, most desktop drives work fine, but you will
>> want to bump up the scsi_command_timer attribute in the kernel for them (200
>> seconds is reasonable, just make sure you have good cables and a good
>> storage controller).
>> 4. Avoid WD Green drives, without special effort, they will get worse
>> performance and have shorter lifetimes than any other hard disk I've ever
>> seen.
>> 5. Generally avoid drives with a capacity over 1TB from manufacturers other
>> than WD, HGST, and Seagate, most of them are not particularly good quality
>> (especially if it's an odd non-power-of-two size like 5TB).
>
> +1 !  Additionally, is it still the case that it is generally safer to
> buy the largest capacity disks offered by the previous generation of
> technology rather than the current largest capacity?  eg: right now
> that would be 4TB or 6TB, and not 8TB or 10TB.
In general, yes, but you're normally safe as long as you're not using 
SMR disks.  I've used a couple of 8TB non-SMR drives, and they work 
perfectly fine (although they're insanely expensive), it's just been the 
SMR stuff that's been an issue (and you shouldn't be using them for 
non-archival storage anyway).