----- Original Message -----
From: "Dan Mack" <[email protected]>
To: <[email protected]>
Sent: Saturday, June 08, 2013 4:56 PM
Subject: should TRIM be working on my ZFS L2ARC devices?
Hiya,
Hopefully a simple question on TRIM + ZFS,
I have a couple L2ARCs for a zpool on a test box, two different SSDs:
ada0 at ahcich0 bus 0 scbus0 target 0 lun 0
ada0: <OCZ-VERTEX4 1.5> ATA-9 SATA 3.x device
ada0: 600.000MB/s transfers (SATA 3.x, UDMA6, PIO 8192bytes)
ada0: Command Queueing enabled
ada0: 122104MB (250069680 512 byte sectors: 16H 63S/T 16383C)
ada0: Previously was known as ad4
ada1 at ahcich1 bus 0 scbus1 target 0 lun 0
ada1: <INTEL SSDSC2CW120A3 400i> ATA-9 SATA 3.x device
ada1: 600.000MB/s transfers (SATA 3.x, UDMA6, PIO 8192bytes)
ada1: Command Queueing enabled
ada1: 114473MB (234441648 512 byte sectors: 16H 63S/T 16383C)
ada1: Previously was known as ad6
I'm just using a small piece of each one for the L2ARC per below:
capacity operations bandwidth
pool alloc free read write read write
----------- ----- ----- ----- ----- ----- -----
tron 98.2G 3.53T 7 23 58.2K 970K
mirror 49.1G 1.76T 3 11 29.2K 485K
ada2 - - 1 5 15.4K 485K
ada4 - - 1 5 14.7K 485K
mirror 49.1G 1.76T 3 11 29.0K 485K
ada3 - - 1 5 14.6K 485K
ada5 - - 1 5 15.3K 485K
cache - - - - - -
gpt/larc0 2.89G 29.1G 0 5 9 201K
gpt/larc1 2.12G 29.9G 0 1 9 148K
----------- ----- ----- ----- ----- ----- -----
I'm running 10.0-CURRENT #34 251520 and I never seen any successful trim
events:
kstat.zfs.misc.zio_trim.bytes: 0
kstat.zfs.misc.zio_trim.success: 0
kstat.zfs.misc.zio_trim.unsupported: 102
kstat.zfs.misc.zio_trim.failed: 0
kstat.zfs.misc.zio_trim.unsupported is always > 0 and the other values
stick at 0.
Does the Vertex 4 and Intel 520 not work with TRIM on FreeBSD or is
something else going on here?
Connected to an controller which supports BIO_DELETE yes they
should.
Check with:
camcontrol identify ada0
camcontrol identify ada1
Like, will TRIM only kick in after each device gets full and
pages start getting evicted ?
I would indeed expect ZFS to only evict data from the L2ARC when
it becomes stale, assuming this is the case you may not see TRIM's
as often as you might first expect.
Regards
Steve
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