[DRBD-user] [Fwd: Re: [Linux-HA] heartbeat 2.0.8: lockups] kerneloops

Gerry Reno greno at verizon.net
Wed Feb 21 23:29:12 CET 2007

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


Ross S. W. Walker wrote:
> There is a known bug in the current implementation of MD raid,
> specifically for raid-1 based arrays. The current MD code fails to
> preserve the BIO_RW_BARRIER flag on cloned bios.
>
> What this translates to in DRBD is severe performance penalties and
> possible meta-data integrity issues for meta-data stored on MD raid-1
> volumes.
>
> Please use an alternate location for your meta-data then an MD RAID-1. I
> recommend hardware raid, or LVM-mirror, or standalone disk.
>
> -Ross
>
>   
Do you think this would result in the lockups I'm seeing? I haven't 
noticed any performance issues. Resyncs proceed at about 12MB/s which is 
about all you can get out of gigabit (not) networking.

Are there any patches for the md flag issue? I can move the metadata if 
necessary but a patch to fix the problem would be ok too. I'll probably 
just move it to the root disk. Although, now that I'm looking root 
directory is on a RAID-1 array also. In fact, the whole machine is 
RAID-1 arrays including /boot! Now what do I do?

Gerry




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