Re: mdadm stuck at 0% reshape after grow

[Brad Campbell <lists2009@fnarfbargle.com>]

On 09/12/17 08:20, Edward Kuns wrote:
> On Thu, Dec 7, 2017 at 5:40 PM, Wols Lists <antlists@youngman.org.uk> wrote:
>> 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.