Re: LSI SAS - SSDs with DRAT and DZAT

[Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>]

On 02/12/2014 03:27 AM, Kurt Miller wrote:
> I can report that the Samsung 840 Pro*does*  support trim on the LSI
> SAS2008. As suspected it supports deterministic read zeros after trim.
>
> One other thing to note, in my testing the P16 LSI firmware has broken
> trim support. P14 and P15 report incorrect values for
> /sys/block/sdX/queue/discard_granularity. P17 and P18 appear to work
> fine and report correct values for discard_granularity.

We are just looking for SSDs for our new compute cluster and would like 
to get SSDs that support trim on LSI sas controllers out of the box.
Unfortunately, for a test sample of Samsungs MZ7WD240HCFV discard is not 
enabled by default, so probably DRAT and DZAT are missing
(I can't test that right now, as 'hdparm -I' does not seem to work with 
devices attached to the controller).

A colleague just told me that Samsung 840 Pro are also not an ideal 
option, as these have set overprovisioning to 0 bytes by default and 
there only seems to be windows tool to set it to a higher value. Not a 
nice idea if you want to do that for dozens or hundreds of drives.

Any other suggestions for ~240GB SSDs supporting DRAT and DZAT or 
trim-on-lsi-sas in general? The LSI support link sent by Kurt [1] is 
also not perfect with respect to trim, as it lists Intel510, although we 
definitely know that Intel510s are disabled by default and forcing 
write-same trim causes data corruption (unmap works, though).


Thanks in advance,
Bernd


[1]
> http://www.lsi.com/downloads/Public/Host%20Bus%20Adapters/Host%20Bus%20Adapters%20Common%20Files/LSI_6Gb_SAS_SATA_HBA_Compatibility_List.pdf