[DRBD-user] Uncatchable DRBD out-of-sync issue

[Maurits van de Lande]

>> there is a certain risk of data not reaching the hard disk soundly.
>It seems so but what is a way to catch the reason?

If you use LVM, did you set the correct filter in lvm.conf?
Edit
/etc/lvm/lvm.conf
And allow only “drbd” devices  to be used for LVM
    filter = [ "a|drbd|", "r|.*|" ]
Turn off LVM cache
write_cache_state = 0

Do you use some custom disk caching module like flashcache?
I have had data integrity issues when I used flashcache with drbd.

>> - not use dual-primary
>I can't because I need online migration (I know it's dangerous to do migration now, because data can be not synced properly)
To avoid the dual primary mode I have put all storage on an a HA iSCSI SAN, then drbd can be used in primary/secondary mode. If you want I can send you my setup notes using centos 6.4 drbd, tgt and pacemaker.

Best regards,

Maurits van de Lande

Van: drbd-user-bounces at lists.linbit.com<mailto:drbd-user-bounces at lists.linbit.com> [mailto:drbd-user-bounces at lists.linbit.com] Namens Stanislav German-Evtushenko
Verzonden: maandag 25 maart 2013 10:43
Aan: Felix Frank
CC: drbd-user at lists.linbit.com<mailto:drbd-user at lists.linbit.com>
Onderwerp: Re: [DRBD-user] Uncatchable DRBD out-of-sync issue

Hi,

> there is a certain risk of data not reaching the hard disk soundly.
It seems so but what is a way to catch the reason?

> What's your hard disk stack?
RAID 1+0 on both nodes.

> If you have the freedom, there are some things to try, e.g.
> - not use ethernet bonding
I can try but it will decrease bandwidth from 200MiB/s to 100MiB/s and disable redundancy.
> - not use dual-primary
I can't because I need online migration (I know it's dangerous to do migration now, because data can be not synced properly)

> - use a smaller partition
Why?

Best regards,
Stanislav
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