DRBD perfs with different kind of disk for each node

[Fred91]

Hello,

I plan to install a proxmox cluster with one node for production and ont node for backup. I will use drbd.

The fisrt server will use 15krpm SAS disks while the backup server will use standard SATA 7,2krpm.

When the main server will write to the DRBD volume, will it have to wait that the second node is synchronized ? In other term, are DRBD performances on one node depending on the slowest node ?

Thanks for your advices,

Fred

 

[bohansen]

Yes and no. If you run a syncronized setup (protocol C in drbd) you will have to wait for the second node. However if you are using hardware RAID controller with BBU you might not be hit that hard - even though if you try to stream a large file I guess your limit will be the SATA drives.
Another (and recommended) way to do this is to have two identical servers and split the drives into two DRBD volumes. In this way you can have a bunch of VMs running on each server without getting complicated split brain situations with DRBD. This also makes your second server do something better than idle ;-).

Bo

 

[giner]

As well you will probably use syncer rate that will be less then disk performance.
http://www.drbd.org/users-guide/s-configure-syncer-rate.html