[DRBD-user] The Problem of File System Corruption w/DRBD

Eric Robinson eric.robinson at psmnv.com
Thu Jun 3 14:50:18 CEST 2021

> -----Original Message-----
> From: Digimer <lists at alteeve.ca>
> Sent: Wednesday, June 2, 2021 7:23 PM
> To: Eric Robinson <eric.robinson at psmnv.com>; drbd-user at lists.linbit.com
> Subject: Re: [DRBD-user] The Problem of File System Corruption w/DRBD
> On 2021-06-02 5:17 p.m., Eric Robinson wrote:
> > Since DRBD lives below the filesystem, if the filesystem gets
> > corrupted, then DRBD faithfully replicates the corruption to the other
> > node. Thus the filesystem is the SPOF in an otherwise shared-nothing
> architecture.
> > What is the recommended way (if there is one) to avoid the filesystem
> > SPOF problem when clusters are based on DRBD?
> >
> > -Eric
> To start, HA, like RAID, is not a replacement for backups. That is the answer
> to a situation like this... HA (and other availability systems like RAID) protect
> against component failure. If a node fails, the peer recovers automatically
> and your services stay online. That's what DRBD and other HA solutions strive
> to provide; uptime.
> If you want to protect against corruption (accidental or intentional, a-la
> cryptolockers), you need a robust backup system to _compliment_ your HA
> solution.

Yes, thanks, I've said for many years that HA is not a replacement for disaster recovery. Still, it is better to avoid downtime than to recover from it, and one of the main ways to achieve that is through redundancy, preferably a shared-nothing approach. If I have a cool 5-node cluster and the whole thing goes down because the filesystem gets corrupted, I can restore from backup, but management is going to wonder why a 5-node cluster could not provide availability. So the question remains: how to eliminate the filesystem as the SPOF?

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