El mié, 03-03-2010 a las 11:16 -0800, Michael @ Professional Edge LLC escribió:
Hail Linux Cluster gurus,
[...]
From what I can find messing with Luci (Conga) though... is - I don't see any resource scripts listed for - "mdadm" (on RHEL 5.4) - so would my idea even work (I have found some posts asking for a mdadm resource script but I've seen no response)? I also see with RHEL 5.3 LVM has mirrors that can be clustered now - is this the right answer? I've done a ton of reading but everything I've dug up so far; assumes that the fiber devices are being presented by a SAN that is doing the redundancy before the RHEL box sees the disk... or... there are a ton of examples of where fiber is not in the picture and there are a bunch of locally attached hosts presenting storage onto the TCP (ethernet) - but I've not found nearly anything on my situation...
You can find an unofficial MDADM rgmanager resource script at this topic:
https://www.redhat.com/archives/linux-cluster/2009-August/msg00111.html
The resource was developed by Brem Belguebli, maybe if he sees this topic he could give you more detail of the capabilities of the resource script and it's compatibility with LVM / CLVM on top of it.
In the other hand, you can use directly mirrored LVM volumes with CLVM. I made some testing with the behaviours of mirrored LVM and I found some strange stuff when only one node fails its connection to the device - in your situation it will happen when one of the nodes fails one of the links with one of the shelves. The fact was the device being marked as "unknown device" in the node with the failed path, and in the other everything seemed ok. What can happen during the "reconstruction" of the failed volume can be unpredictable. Note the "99.6" in the Copy% column, it always had the same value while the path was failed:
NODE A
lvs -a -o +vg_name,device
LV VG Attr LSize Origin Snap% Move Log Copy% Convert VG Devices
logvolquorum volgrp01 mwi-ao 996,00M logvolquorum_mlog 100,00 volgrp01 logvolquorum_mimage_0(0),logvolquorum_mimage_1(0)
[logvolquorum_mimage_0] volgrp01 iwi-ao 996,00M volgrp01 /dev/mpath/quorum01(0)
[logvolquorum_mimage_1] volgrp01 iwi-ao 996,00M volgrp01 /dev/mpath/quorum02(0)
[logvolquorum_mlog] volgrp01 lwi-ao 4,00M volgrp01 /dev/mpath/logquorum01(0)
NODE B (failed path)
lvs -a -o +vg_name,device
LV VG Attr LSize Origin Snap% Move Log Copy% Convert VG Devices
logvolquorum volgrp01 mwi-ao 996,00M logvolquorum_mlog 99,60 volgrp01 logvolquorum_mimage_0(0),logvolquorum_mimage_1(0)
[logvolquorum_mimage_0] volgrp01 Iwi-ao 996,00M volgrp01 /dev/mpath/quorum01(0)
[logvolquorum_mimage_1] volgrp01 Iwi-ao 996,00M volgrp01 unknown device(0)
[logvolquorum_mlog] volgrp01 lwi-ao 4,00M volgrp01 /dev/mpath/logquorum01(0)
I hope this brings some light to your questions.
Cheers,
Rafael
-- Rafael Micó Miranda |
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