Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On 22/12/16 04:22 PM, Bart Coninckx wrote: > -----Original message----- > *From:* Digimer <lists at alteeve.ca> > *Sent:* Thu 22-12-2016 20:55 > *Subject:* Re: [DRBD-user] secondary DRBD node shows UpToDate but is not > *To:* Bart Coninckx <info at bitsandtricks.com>; drbd-user at lists.linbit.com; > On 21/12/16 08:55 AM, Bart Coninckx wrote: >> Hi all, >> >> since a couple of years we have a 2 node DRBD cluster on CentOS 6.5 and >> DRBD (version: 8.4.5 (api:1/proto:86-101)) installed from source. We >> noticed that all DRBD resources show "UpToDate" on the secondary node, >> but if we restart the service, one or more resources start syncing >> again, indicating there seem to be differences in between the resources. >> This is of course not desirable. >> >> Is this a known issue with this version? If needed we will upgrade the >> cluster, but since a complete virtualization setup is running on top of >> it, this is not evident, hence the reason why I inquire first about >> possible known issues. >> >> Cheers, > > Might not be helpful, but have you tried running a verify? > > https://www.drbd.org/en/doc/users-guide-84/s-use-online-verify > > -- > Digimer > Papers and Projects: https://alteeve.ca/w/ > What if the cure for cancer is trapped in the mind of a person without > access to education? > > > > Hi, > > thank you Digimer. That seems like a decent workaround, if we automate > it. But it is just that of course. If disaster strikes in between > verifies, I believe we still have a problem, correct? > > Cheers, I've run DRBD from 8.3.7 to the latest 8.4 going back many years. Only once have I had a problem, and I am pretty sure it is because the node's storage controller acted up. DRBD should always write the same data to both nodes all the time. However, if the backing device flips some bits, then the data on the backing device might differ from what is expected. This is fundamentally a hardware problem (or low level software issue, below DRBD). Running a verify once a month is probably a good idea if you are worried, and it would be similar to how mdadm runs a verify monthly. I don't believe this is a DRBD issue itself, but DRBD can help protect against it. -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education?