[DRBD-user] Questions I'm sure have been asked before..

Helmut Wollmersdorfer helmut.wollmersdorfer at gmx.at
Mon Jun 6 14:39:24 CEST 2005

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

nick wrote:

> I've got two identical machines (pentium 4, 2 80 gb SATA drives, 512mb 
> ram, drbd 0.7.10, CentOS 3.3, although with the ultramonkey kernel for 
> the heartbeat integration) which will be running as HA mailservers, with 
> two DRBD drives drbd0 which will contain /var and drbd1 which will 
> contain /home. The idea behind my setup is to make sure that no mail 
> gets lost either from the spool or the home users drives in case of a 
> system failure.

I don't know, what you have in /var, but usually there will be e.g. 
/var/log/syslog which is not a good idea to mirror. If you only want to 
mirror your mails, mirroring /var/mail should be enough.

> The drbd drives will be running on top of two Raid partitions /dev/md2 
> and /dev/md3, I've created two 150mb partitions for the meta data, 
> /dev/sda7 and /dev/sdb7.

> The thing is, I already have data and a filesystem present on md2 and 3, 
> ext3 to be exact, and most of the replies I've seen on this subject seem 
> to be aplicable to people with internal metadata, in that they advise 
> shrinking the filesystem first (I'm assuming here, correct me if I'm 
> wrong).

If you have metadata external you need not shrink the filesystem.

> Before I take the leap in changing my fstab, and mounting the drbd 
> drives, what exactly do I need to know, then do? I'd prefer not to lose 
> any data (although it wouldn't be the end of the world), and I'm not 
> sure exactly what effect creating a filesystem would have on the 
> existing data. I'd be glad to read up on it, if anyone has any pertinent 
> links.

If you 'create' a filesystem, i.e. doing 'mk2fs', on a partition with 
existing data, you will get an empty filesystem anyways.

> Also, I could use some more information on heartbeat integration, most 
> of the ones I've seen list datadisk, but in my /etc/ha.d/resource.d/ 
> there's a drbddisk, is this the same thing? 

Since DRBD 0.7.x drbddisk is used.

> Does anyone have any links 
> or info I can read which deal witht he latest versions of DRBD and 
> heartbeat?

For e.g. a ha-mailserver you will usually need to configure drbd, 
IP-failover, and the failover of the mailserver-demon.

You should read http://wiki.linux-ha.org/FrontPage and linked documents 

Helmut Wollmersdorfer

More information about the drbd-user mailing list