[DRBD-user] 4TB limit

Ralf Gross Ralf-Lists at ralfgross.de
Thu Oct 19 15:17:19 CEST 2006


Matthias Weigel schrieb:
> 
> LVM on top of DRBD works great for me.
> The only problem is LVM wants to autodetect at startup its configuration 
> using some sort of signature or super block. LVM scanns all available 
> block devices for its signature and refuses DRBD-devices, because they 
> have the same UID as the underlying devices.

Ok.
 
> So you have to make sure, LVM sees ONLY your DRBD-devices and not the 
> devices DRBD uses. This is done in /etc/lvm/lvm.conf with the "filter" 
> statement.

I've put this into lvm.conf

filter = [ "r|/dev/cdrom|", "r|/dev/sd*|", "r|/dev/evms/sd*|" ]

# vgscan -vvvv 2>&1 | grep sd
[snip]
#filters/filter-regex.c:185         /dev/sda: Skipping (regex)
#filters/filter-regex.c:185         /dev/evms/sda1: Skipping (regex)
#filters/filter-regex.c:185         /dev/sda1: Skipping (regex)
#filters/filter-regex.c:185         /dev/evms/sda2: Skipping (regex)
[snip]

I then created the pv with 'pvcreate /dev/drbd0', 'pvcreate
/dev/drbd1' on the primary node.  If I check the pv on the secondary I
get this:

# pvdisplay
/dev/drbd0: read failed after 0 of 4096 at 0: Input/output error
/dev/drbd1: read failed after 0 of 4096 at 0: Input/output error

[after 5 minutes of meditation...]

That's perfectly ok. After changing primary/secondary state of both
nodes the output of pvdisplay has changed as expected ;)

Creating a vg and lv works, changing the state of primary and
secondary after 'vgchange -a n vg01' on primary too.

Next I will try to add a 3. drbd device and extend the lvm and the
filesystem.

ralf




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