[DRBD-user] drbd EXT3 filesystem issues

Lars Ellenberg lars.ellenberg at linbit.com
Fri Oct 31 16:08:42 CET 2014

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

On Sun, Oct 26, 2014 at 03:17:39PM +0000, Oren wrote:
> Hi,
> We are experiencing allot of filesystem issues, for example:
>  kernel: EXT3-fs error (device drbd0): ext3_free_blocks_sb: bit already cleared for block 5776787
> These occur randomly after several consequative failovers between the cluster nodes.
> We are using drbd with ext3 filesystem with a write-through controller.
> Are there any preferences what elevator we should use?
> According to http://www.drbd.org/users-guide/s-latency-tuning.html 
>  both cfq/deadline are fine with preference to deadline.
> But both re-order writes, right?


> possibly breaking file system/journal on standby.

Not at all.

Unless you configure DRBD for "no disk drain",
so don't do that.

We analyse the incoming request stream,
automatically detect re-order-domains,
and separate those with in-drbd-wire-protocol "drbd barrier" packets.

> Please advise,
> Setup
>  drbd with ext3 filesystem 
>  write-through controller
>  Two nodes cluster
>  Physical Appliances
>  CentOS 6.2 with 2.6.32-220
>  kmod-drbd83-8.3.12-1.el6.i686

Please use drbd 8.4.
You will be so much more happy.

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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