SATA vs SAS drives for RAID (Threaded from Thoughts on VTL solutions)

EXCELLENT question sir!

SATA is designed for PCs. As such if there is an error it tries again. Seems like a good idea and often given sufficient retries the drive will actually return data. When that's your data it's good news! With PCs they rarely have data protection so there is really little other choice and it boils down to 'get my data or I'm in deep weeds!'

SAS on the other hand is designed for servers. There are some performance improvements and command capabilities and those do matter. However, the important thing is that when there is an error, SAS will return the error up the chain after a defined number of retries is exhausted.

Why is the error handling important? Because with RAID when you have a drive failure then you want to know that and replace the critter. If it's SATA the controller may be stuck waiting for the drive to respond as it continually attempts to find that data. With SAS the error is returned to the controller and the drive can be flagged and thus replaced. Until it is though the controller can happily operate using the RAID data to keep returning data and accepting writes.

Side note: As it works out virtually all SAS controllers can also control SATA drives since the capabilities of SATA are a subset of SAS.

- Larry "DrFranken" Bolhuis

www.Frankeni.com
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On 5/9/2020 6:03 AM, Gad Miron wrote:

Both the SPHiNX and Cybernetics units are available in various sizes of
rack-mounted units from 1 to 4 U, redundant power, various RAID
selections and generally use 7.2K RPM SAS drives (You NEVER want to use
SATA drives in RAID. Don't do it)

- Larry "DrFranken" Bolhuis

Just plain curiosity, why not use SATA drives with RAID ?

Gad