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
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