Toolserver:Replication lag

Toolserver uses database replication to mirror the Wikimedia database used by the live servers. Each update to the live database is logged, and the Toolserver databases follow this log to make the same updates. The Toolserver databases may fall behind the Wikimedia database, resulting in a situation where the toolserver data represents the state of the Wikimedia database some time in the past. The replication lag (replag) tells how far behind the Wikimedia databases the Toolserver databases have fallen. Database crashes and expensive queries can cause the replag to dramatically increase.

The current replag can be viewed here or there, or by typing @replag in the #wikimedia-toolserver IRC channel on freenode.

When invoked, the replag bot (currently tsbot) will output something like this: s1: 4h 8m 58s [+1.03 sec/sec]; s1-c: 2s [-1.09 sec/sec]; s2: 2s [+0.06 sec/sec]; s3: 4s [-0.63 sec/sec]; s3-c: 10h 51m 27s [+0.03 sec/sec] (59s sample)

This shows the amount of lag on s1, s2, and s3 and the rate of change for each. It also shows the amount of lag of for the Commons replications (s1-c and s3-c). S3's copy of Commons is ancient and should not be used.