Re: filesystem dead, xfs_repair won't help

Eric Sandeen
2017-04-12T15:34:49Z

On 4/12/17 10:15 AM, Christoph Hellwig wrote:
> On Tue, Apr 11, 2017 at 11:48:19AM -0500, Eric Sandeen wrote:
>> As an experiment, though, if you want to play, it might be interesting to
>> mkfs.xfs it with a 4096 byte sector size, and see if that makes it happier.
>> By default, xfs is doing metadata IO in 512 chunks, something other filesystems
>> won't do by default.
>>
>> I guess you don't know how to provoke the corruption, though, to be able
>> to run that test reliably...
>
> Btw, it might be a good idea to move to 4k sector size as the default,
> on pretty much any modern hardware sector sizes are 4k or larger
> internally, and 512 byte writes will always involve read-modify-write
> cycles. And unlike SATA or SCSI disks NVMe doesn't have a physical
> block size attribute, so we can't even look at that.

Is it safe to do that on a device that /actually/ has only 512 sectors?

I /think/ Brian's tear detection helps, but </handwave> is it legit
to do metadata IO larger than the fundamental IO size of the storage?

-Eric