Author Archive

Hot backup for KVM / libvirt / Xen

Overview We use Xen server on our development server and I decided, it’s time I start making full snapshots of my VM’s. So far we’ve done data backup only, mainly because of storage limitations. Since we got the new server, I have much more disk space now, so I would like to backup whole VM’s.

Converting your InnoDB MySQL server to TokuDB (how we did it)

What is TokuDB? TokuDB is a storage engine for MySQL and MariaDB that dramatically improves the performance of large databases (typically 50 GBs or larger). By replacing 40-year-old B-tree technology with patented Fractal TreeĀ® technology, TokuDB speeds indexing by 10x or more, and reducing the size of the database by upt o 90%. Because of

Tracing I/O usage in Linux

Introduction We know quite few programs that help us identify I/O usage in Linux. In order to identify exactly what is writing and which process, we need to use quite few commands, to make sure we know exactly what is going on. I will show you few useful commands that will help you find your

Restoring deleted/resized logical volume

Calm yourself down Congratulations, you managed to accidentaly remove useful logical volume! No worries! Calm down, it’s all fine, we’ll get it back in few simple steps. Luckily, LVM archives all removed logical volumes when you make lvremove. In order to get it back we can use LVM’s native commands. All we have to do,

ip_conntrack: table full, dropping packet / conclusions about connection tracking

The problem Recently one of our clients started a very large campaign and my servers got hit by twice the traffic it was handling normally. We actually didn’t have any problems, but from time to time you would notice this error message on our main firewall: ip_conntrack: table full, dropping packet Investigation I have seen this