[DRBD-user] Using DRBD for Backup and Cheap SAN ?

Christoph Adomeit Christoph.Adomeit at gatworks.de
Fri Sep 7 21:25:18 CEST 2007

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

Hi there,

I have to plan some 10 Linux Servers in 1 Location. The Servers do
webhosting, typo3-hosting, so mysql-stuff, mailserver, antispam,
imap mailboxes,virus checks and all that stuff. The average needed diskspace
per host is about 25 GB. The need for heartbeat and immediate automagic
failover is not there.

I want to consolidate these servers to 2-3 xen hosts and normaly I
should use a SAN, but a SAN is too expensive for this setup.

So I played around with AOE, ISCSI, GNBD and such stuff but they
are all not fast enough and not reliable enough for me. So my
conclusion is, that ethernet-storage is not an option (except drbd
which is fast and reliable).

Here drbd comes to my mind. My idea is basically:

-Run the stuff on the Xen-Hosts and the VMs under LVM on cheap local 
harddisks for performance reasons.
-Replicate each logical volume via drbd to one or 2 storage hosts
so that we have a current-copy in case of a crash.
-In case of a crash of a xen host I could copy the logical volumes
(xen vms) from the storage host to another host with another cheap 
harddisk or just mount the drbd partition from the storage host 
and continue running the server.

My next idea is to speed up backups. The Network Amanda Backups of
the xen hosts take a lot of time and I don't want to backup 
Servers via Network anymore. With the above idea i might be able to backup the
vms right from the Storage hosts.

Maybe I could even run the drbd in master-master mode and backup a 
snapshot of the drbd partition instead of the drbd partition.

What do you think about the above ideas ? Do they make sense ?



More information about the drbd-user mailing list