TRIM support through ciss

[Steven Hartland]

----- Original Message ----- 
From: "Dmitry Morozovsky" <marck at rinet.ru>
To: <freebsd-stable at FreeBSD.org>
Sent: Wednesday, June 05, 2013 11:00 PM
Subject: TRIM support through ciss


> 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?

What your seeing there is that the RAID array doesn't support
any DELETE methods.

For ZFS you really don't want to use a HW RAID, its much better
to just give ZFS the raw disks as you gain nice features like
self healing :)

I've never used ciss, but if you can configure the disks as
JBOD it may mean it can then support a delete method.

In addition for TRIM to work all data disks in a pool need to
support a delete method. L2ARC disks are treated seperately.

    Regards
    Steve

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