Where does my instance run?
Several way to know where your instances run.
NFS attribute caching performance impact on web applications
A couple of days ago, I had some issues with NFS consistency, not every servers were up to date. Some servers had the good version of the file some hadn’t. However performing a ls -l seemed to fixed tempory the problem after each update (where a simple ls didn’t). Indeed issuing ls with the -l option triggers stat() where ls doesn’t, just because file attributes are called from the stats() function. I needed to investigate…
Cleanup keystone tokens
Every once in a while you really want to cleanup the token table of the Keystone database. A couple of weeks ago while backuping my cloud controller I noticed that the backup of the Keystone database was longer than the other databases. After that, I checked the size of the dump (compressed) 60MB. Hummm but there is almost nothing in the Keystone database: users, tenants… wait.. could it be TOKENS?!
OpenStack: perform consistent snapshots
Make consistent instance or volume snapshots.
Ceph: manage storage zones with CRUSH
This article introduces a simple use case for storage providers. For some reasons some customers would like to pay more for a fast storage solution and other would prefer to pay less for a reasonnable storage solution.
Openstack and rsyslog
I don’t want to see my logs poluted by INFO messages saying “hey, I’m running!”. No thanks, it burns my I/O cycles for nothing. If it doesn’t work I have a monitoring system for that and if it’s broken I simply change the log level to DEBUG. Of course it’s personal thoughts, however for those you who are interested just click ;-).
Ceph and MDS
I’ve been often asked a couple of time, why CephFS is not ready? Does this statment is still true?
Last friday failover and Stonith were evil...
Friday, end of the week, almost week-end, almost time to enjoy the warm weather of my hometown and yet…
Make your RBD fly with flashcache
In this article, I will introduce the Block device cacher concept and the different solutions available. I will also (because it’s the title of the article) explain how to increase the performance of an RBD device with the help of flashcache in a Ceph cluster.
Tip: OpenStack Retrieve usage statictics
While waiting for the Ceilometer project to be ready, nova provides some facilities to retrieve simple statistics. A little overview about the available commands.