Cache in Openfire

In the course of troubleshooting the office Jabber server the other day, I came across some interesting info about the various caches that Openfire has. If you log on to the admin console of your Openfire server and go to the cache summary page, you can see what the usage and effectiveness of your various caches are. Specifically, I found that a couple caches were full - Roster and VCard. The Roster cache was limited to 0.50MB by default it seemed and it's effectiveness was less than 20% at the time.

It is a fairly common issue and it has been discussed in the Ignite Realtime forums. The solution posted is to set a couple system properties to override the default:

cache.username2roster.size
cache.vcardCache.size

Both of these are given in bytes. The post in that thread says to go to 5MB, I found that my Vcard cache didn't need to be much bigger than the default and the roster cache only needed 2 or 3 MB.

After changing this, both cache hit rates are closer to 90%.

Our system is very small (less than a couple hundred users total), so the effect is not big on regular usage. But well worth checking on your server as it is a quick and easy optimization.

Again with the tapes

In a previous post I said that to get around devices changing their numbering, it was useful to use the /dev/tape/by-id instead of the generic /dev/nst0. Unfortunately, this is also imperfect I've just learned as the device which was previously "scsi-35000e11138aa0001-nst" this time came up as "scsi-35000e11138aa0001". And you can guess how gracefully the software handled that (not at all). Now I don't know if was a driver update (possible) or if the device was switched to a different SAS interface (also possible), or maybe just the gremlins. Whatever it was, once again, I had to reconfigure the software to find the new device ID.