On 09/12/17 08:20, Edward Kuns wrote:

On Thu, Dec 7, 2017 at 5:40 PM, Wols Lists [off-list ref] wrote:

quoted

But if this is true, for a drive that doesn't support sct (I don't have
one to test), the command will fail but return 0!!! So the script
doesn't realise anything is wrong, doesn't fix the defaults, and leaves
the raid array in the dangerous situation where linux will time out long
before the drive does.

So does smartctl return 0 if the drive doesn't support sct? If so why?
And what's the easiest way to detect such a drive if so?

I can reproduce this on a Samsung 830 SSD (released in 2011, probably
purchased in 2012).  I also have an 840 Pro SSD which does not have
this problem -- it fully supports SCTERC being set.  I don't know how
representative of SSD models these two are, but that gives a time
frame for this support appearing in SSD drives.

I can go with that. I wrote that script snippet, and yes on my box with 
3 Samsung 830 drives it reports them as good. I never bothered to check 
whether it was valid as I really only cared about setting the correct 
values for the spinning disks.

root@srv:~# smartctl -x /dev/sdc | egrep '(Device Model|SCT)'
Device Model:     SAMSUNG SSD 830 Series
SCT Commands not supported

I never claimed it was perfect, just "good enough for me(tm)".

I only had 40 or 50 disks of about 3 different manufacturer and 5 
different model to test with, so my sample space was pretty low.

Brad.