[dm-devel] Simulating faulty disk

[Bryn M. Reeves]

On 10/21/2011 03:47 PM, Yathindra wrote:
> dmsetup create d0 --table="0 `blockdev --getsize /dev/sdb` delay
> /dev/sdb 0 500"
> dmsetup create f0 --table="0 `blockdev --getsize /dev/mapper/d0` flakey
> /dev/mapper/d0 0 9 1"
> mkfs -t ext3 /dev/mapper/f0
> ...
> ...
> ext2fs_mkdir: Attempt to read block from filesystem resulted in short
> read while creating root dir
>
> Can we even mount such a device ?

It's a flakey device :)

With that table you'll have a device that is failing write I/Os for 1s 
in every ten. If that coincides with mkfs trying to write to the device 
it will create a corrupted file system.

Depending on what you are trying to test you may want to put data on the 
device first.

Regards,
Bryn.