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To: Jeffrey Hundstad <jeffrey.hundstad@xxxxxxxx>
Subject: Re: TRIM on XFS
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 11 Oct 2011 13:05:52 +1100
Cc: xfs@xxxxxxxxxxx
In-reply-to: <4E936BFB.5060907@xxxxxxxx>
References: <201110071352.20135@xxxxxx> <20111007233450.GK3159@dastard> <201110100829.45823@xxxxxx> <CAGpXXZJs8kjZaSp248rA+-d=gpwWe=oK0xtUUirv+zgE3Vq3kA@xxxxxxxxxxxxxx> <4E936BFB.5060907@xxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Mon, Oct 10, 2011 at 05:04:43PM -0500, Jeffrey Hundstad wrote:
> On 10/10/2011 03:28 PM, Greg Freemyer wrote:
> >fitrim is the batch mode.
> >
> >To enable realtime discard, add --discard to your mount options.
> >
> >Documented 
> >athttp://lxr.linux.no/#linux+v3.0.4/Documentation/filesystems/xfs.txt
> >
> >To invoke batch mode, simply use fstrim from user space.
> Hello,
> I'm also trying to use FITRIM on a simple XFS partition on a
> spinning magnetic hard drive (remember those).  I haven't had much
> luck.  I'm doing this just to get used to the commands when using
> this against a thinly provisioned disk.  I have no idea if this
> should work in this configuration.
> On a Debian system with Linux 3.0.0-2-amd64 when I issue:
> # fstrim /
> I receive:
> fstrim: /: FITRIM ioctl failed: Operation not supported
> With an strace this looks like:
> open("/", O_RDONLY)                     = 3
> ioctl(3, 0xc0185879, 0x7fff4ea851b0)    = -1 EOPNOTSUPP (Operation
> not supported)

It means the block device underneath the filesystem doesn't support
the TRIM operation. Check /sys/block/<dev>/queue/discard_max_bytes -
if the value is zero then your device doesn't support discard


Dave Chinner

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