Samsung 830 and ZFS TRIM

Steven Hartland killing at
Thu Nov 29 09:49:32 UTC 2012

Do you have any other disks in the machine if so its likely these are
the source of the unsupported increments.


----- Original Message ----- 
From: "Johannes Dieterich" <dieterich.joh at>
To: <freebsd-current at>
Sent: Monday, November 26, 2012 7:48 PM
Subject: Samsung 830 and ZFS TRIM

> Hello,
> (initially posted this to -questions@ a week ago, w/o reply)
> I installed CURRENT on a new Thinkpad equipped with a Samsung 830 SSD:
> ada0 at ahcich0 bus 0 scbus0 target 0 lun 0
> ada0: <SAMSUNG SSD 830 Series CXM03B1Q> 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: 1H 63S/T 16383C)
> ada0: Previously was known as ad4
> as the setup is ZFS+GELI based (on ada0), I enabled ZFS TRIM support in 
> loader.conf.
> Interestingly, I encounter an IMHO strange behavior with the stats on that:
> kstat.zfs.misc.zio_trim.zio_trim_bytes: 755712
> kstat.zfs.misc.zio_trim.zio_trim_success: 97
> kstat.zfs.misc.zio_trim.zio_trim_unsupported: 7891
> kstat.zfs.misc.zio_trim.zio_trim_failed: 0
> It seems unintuitive to me why the unsupported counter first increases 
> (seems to stay constant after that each boot) and then slowly the 
> success counter increases as well.
> Probably there is a trivial explanation (GELI?) and/or fix for this that 
> anyone is willing to share?
> If you need further information, let me know.
> Thanks a lot
> Johannes
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