Hi Bryn,
Sorry to disturb you again. I tried to create a delay device below but
it failed.
>dmsetup create d0 --table="0 `blockdev --getsize /dev/sdb` delay
/dev/sdb 0 500"
device-mapper: reload ioctl failed: Invalid argument
Command failed
In /var/log/messages I see this,
device-mapper: ioctl: error adding target to table
>uname -r
2.6.32-24-generic-pae
>dmsetup --version
Library version: 1.02.39 (2009-10-26)
Driver version: 4.15.0
Am I doing something wrong.
Thanks,
Yathi
On 10/20/2011 9:56 AM, Bryn M. Reeves wrote:
On 10/20/2011 04:45 PM, Yathindra wrote:
Hi Bryn,
Thanks for that info. Could you please tell me where I can find more
details about using it.
Thanks again,
Yathi
There's a couple of brief files describing the targets in the
Documentation/device-mapper directory:
http://www.kernel.org/doc/Documentation/device-mapper/dm-flakey.txt
http://www.kernel.org/doc/Documentation/device-mapper/delay.txt
They both work like the linear target (except that they introduce the
specified faults according to their parameters).
To set up a device with both you'd need to use a pair of stacked
devices so something like:
dmsetup create d0 --table="0 $SECTORS delay $DEVICE 0 500"
dmsetup create f0 --table="0 $SECTORS flakey /dev/mapper/d0 0 9 1"
This will create a device /dev/mapper/f0 that is drops out for 1s in
every 10 and has a 500ms delay on reads and writes. SECTORS is the
size of the underlying device in sectors (use e.g. $(blockdev
--getsize)).
You can optionally specify separate delays/device for writes to the
delay layer and write loss / write corruption for the flakey layer -
see the doc files and also the comments above flakey_ctr and delay_ctr
for more details.
Regards,
Bryn.
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