TRIM on XFS

[Jeffrey Hundstad]

Dave,

Thank you.  I suspected this may be the case.  It is awfully nice to 
have a definitive answer though.  It is especially nice to have a way to 
determine if it is possible.  Thank you!

I've created a an XFS Wiki page for this info:
     http://xfs.org/index.php/FITRIM/discard

-- 
Jeffrey Hundstad

On 10/10/2011 09:05 PM, Dave Chinner wrote:
> 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
> operations.
>
> Cheers,
>
> Dave.