[DRBD-user] Shrinking Filesystem

[Ross S. W. Walker]

> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com 
> [mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of CA Lists
> Sent: Friday, June 22, 2007 10:24 AM
> To: drbd-user at lists.linbit.com
> Subject: [DRBD-user] Shrinking Filesystem
> 
> I have two iSCSI targets that I have drbd 8.0.3 running on 
> (CentOS 5). I'm
> using OCFS2 on my nodes. My question is, which filesystem do I need to
> shrink for DRBD? Do I want to shrink the iSCSI disk on the nodes
> (/dev/sdb1), the actual block device on both iSCSI targets 
> (/dev/sdb), or
> the drbd device on the iSCSI targets (/dev/drbd0)? And can I 
> do this after I
> have used OCFS2 to format the disk? Thanks,

You can't shrink OCFS2, but if you did then your setup doesn't lend
itself well to this.

I recommend a setup like this:

iSCSI SAN, say you have a RAID50 with 1.3TB of storage and a RAID10
with 500GB of storage on your iSCSI server.

Create 2 VGs, 1 called say RAID50.1 another called say RAID10.1 out
of each hardware array PV (say /dev/sdc and /dev/sdd).

Say you then had 2 clusters using these volumes, there are a couple
of ways of slicing it up, but I would probably allocate a whole
block of storage for each cluster based on current needs and expected
growth and let the clusters further divide it up on their end with
CLVM and GFS or LVM and OCFS2.

So maybe create 2 LVs on raid50.1 and 2 LVs on raid10.1:

cluster1.data and cluster2.data on raid50.1
cluster1.log and cluster2.log on raid10.1

On the cluster nodes these would appear as say /dev/sdc and /dev/sdd.

I would then create 2 VGs on the clusters called, data.1 and log.1
out of the 2 iSCSI drives.

>From those I can then allocate on the cluster side the shared
file systems needed, grow and shrink them as I see fit without
having to involve the iSCSI target or drbd in the process.

-Ross

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