[DRBD-user] Drbd io wait ?

Joseph L. Casale jcasale at activenetwerx.com
Thu Apr 29 12:16:18 CEST 2010

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

>I seem to be having a problem with load. I have four servers.
>Two are web servers and the other two are MySQL (Master - Master 
>Replication) and NFS servers. Between the two SQL, I have DRBD running 
>in Active / Passive setup.

So MySQL is Master/Master, but drbd is Active/Passive? What is writing to

> On the passive DRBD machine, I find that, 
>when I do a 10GB Mylvmbackup of Mysql DB, the load on the two webservers 
>go through the roof.
>My question is, could it be the syncing of DRDB and IO wait, that is the 
>reason for this. Or how could I rule out DRDB as the culprit.
>If anyone could help it would be appreciated.

If drbd is active/passive, then you aren't mounting the secondary repl partner
therefore it's not critical for the operation: Stop it and run your test evaluating

You can also use tools like iostat to determine whats being written to with
what parameters.

More information about the drbd-user mailing list