DRBD 8.4.1 introduces a new feature:
read-balancing, which is configured in the
disk section of the configuration file(s). This feature enables DRBD to balance read requests between the Primary/Secondary nodes. Continue reading
Stumbling upon the Holy time-travellin’ DRBD, batman! blog post there’s only one thing to be said …
Be strict in what you emit, liberal in what you accept
is simply not true when dealing with mission-critical systems.
It’s ok to be alerted on upgrading a machine because the “old, working” RegEx that did the parsing doesn’t match anymore; it’s not a problem to get an email when someone adds the 100th DRBD resource and causes the grep to fail; and so on. Continue reading
From time to time we get asked things like this:
I want to use a 10TiB volume with DRBD, is that supported”?
The easiest way to answer things like that is to say look for yourself on the public DRBD usage page – the biggest public device size is ~220TiB, so go figure Continue reading
DRBD tries to ensure data integrity across different computers, and it’s quite good at it.
But, as per the old saying Trust, But Verify it might be a good idea to periodically test whether the nodes really have identical data, similar to the checks that are done for RAID sets. Continue reading
The sync-rate controller is used for controlling the used bandwidth during resynchronization (not normal replication); it runs in the
SyncTarget state, ie. on the (inconsistent) receiver side. Continue reading
The TL;DR version: don’t use
data-integrity-alg in a production setup. Continue reading
For people using the VIM editor I’ve got two small tips when editing Pacemaker configurations:
Use syntax highlight. This helps to see unmatched quote characters easily. Whether it’s too colorful can be discussed, though
A current version can be found here, and the mailing list post is here.
For correlating resource names I recommend the Mark plugin. Continue reading
There is quite a bit of confusion about the DRBD configuration value
al-extents (activity log extents), so here’s another shot at explaining it. Continue reading
Similar to the recent post about setting the
vm.min_free_kbytes value there’s another sysctl that might improve the behaviour: the dirty ratio. Continue reading