[DRBD-user] flashcache + drbd + LVM2 + GFS2 + KVM live migration -> data corruption

Maurits van de Lande M.vandeLande at VDL-Fittings.com
Fri Feb 17 10:36:16 CET 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


I would like to use flashcache te speed up data reads from the drbd disk. Therefore  I have created a "write through" flashcache device
Using :
#/sbin/flashcache_create -p thru -b 16k cachedev /dev/sda1 /dev/sdc1

Then "/dev/mapper/cachedev" is used as a drbd target

on vmhost2a {
    device     /dev/drbd0;
    disk       /dev/mapper/cachedev;
    meta-disk  internal;
on vmhost2b {
    device    /dev/drbd0;
    disk      /dev/mapper/cachedev;
    meta-disk internal;

As a test I have a VM which is being ping-ponged between two servers using live migration.
When I perform the test I get a corrupted VM!
See the following post


Without flashcache it works fine.

Does anyone have a  working drbd+flashcache setup?
What do I do wrong?

Best regards,

Maurits van de Lande

| Van de Lande BV. | Lissenveld 1 | 4941VK | Raamsdonksveer | the Netherlands |T +31 (0) 162 516000 | F +31 (0) 162 521417 | www.vdl-fittings.com<http://www.vdl-fittings.com> |

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