TRIM support through ciss

[Jeremy Chadwick]

On Thu, Jun 06, 2013 at 02:00:36AM +0400, Dmitry Morozovsky wrote:
> Dear colleagues,
> 
> I have a DB server with ciss and a bunch of disks (8 SAS + 2 Intel SATA SSD).
> 
> However, this setup does not seem to support TRIM on SSDs:
> 
> kstat.zfs.misc.zio_trim.bytes: 0
> kstat.zfs.misc.zio_trim.success: 0
> kstat.zfs.misc.zio_trim.unsupported: 418
> kstat.zfs.misc.zio_trim.failed: 0
> 
> 
> Excerpt from dmesg about SSD:
> 
> da9 at ciss0 bus 0 scbus0 target 9 lun 0
> da9: <COMPAQ RAID 0 OK> Fixed Direct Access SCSI-5 device
> da9: Serial Number PACCR9SZ7KJS
> da9: 135.168MB/s transfers
> da9: Command Queueing enabled
> da9: 114439MB (234371520 512 byte sectors: 255H 32S/T 28722C)
> da9: quirks=0x1<NO_SYNC_CACHE>
> da9: Delete methods: <NONE(*)>
> 
> the last line bothers me...
> 
> Is there any tuning I missed?

I'm sure Steve will respond, but in the meantime...

I assume this is you running stable/9 with r251419 or newer (which just
got committed a few hours ago)?

I haven't looked at the code, but it is very, VERY important to remember
that you are *always* at the whim of 1) the controller driver (ciss(4)
in this case), and 2) the controller firmware, as to whether or not
certain pass-through commands are supported (in this case, since you
have a SAS controller, this would be accomplished via a SCSI command
that your controller does not support.

Oh, it looks like Steve just replied and said more or less what I did.
:-)

Bottom line as "we" (the royal we, I guess) have been saying for many
years now: any controller which operates in a RAID fashion and does not
support "true JBOD" (meaning the controller acts a generic controller
with no concept of RAID), will almost always get in the way.  Instead,
stick with true non-RAID controllers -- and yes I am aware choices are
limited.

-- 
| Jeremy Chadwick                                   jdc at koitsu.org |
| UNIX Systems Administrator                http://jdc.koitsu.org/ |
| Making life hard for others since 1977.             PGP 4BD6C0CB |