Posts

Benchmarking DRBD

We often see people on #drbd or on drbd-user trying to measure the performance of their setup. Here are a few best practices to do this.  Read more

“umount is too slow”

A question we see over and over again is

Why is umount so slow? Why does it take so long?

Part of the answer was already given in an earlier blog post; here’s some more explanation. Read more

DRBD 8.4.3: faster than ever

For the people who don’t already have DRBD 8.4.3 deployed: here’s another good reason — Performance. Read more

Trust, but verify

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[1. attributed either to Lenin or Kennedy] it might be a good idea to periodically test whether the nodes really have identical data, similar to the checks that are[1. or at least can be] done for RAID sets. Read more

“al-extents” explained

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. Read more

Make the kernel start write-out earlier

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. Read more