[ClusterLabs] two node cluster with clvm and virtual machines

Lentes, Bernd bernd.lentes at helmholtz-muenchen.de
Sat Feb 4 06:47:37 EST 2017

----- On Feb 3, 2017, at 8:38 PM, Digimer lists at alteeve.ca wrote:

>> And if i don't have a non cluster fs like btrfs, but just a plain lv ?
>> Would live migration then be possible ?
>> I'd like to have live migration.
> No. For a short period during the migration, data needs to be writable
> from both nodes at the same time. To do this, you need to mount the FS
> on both nodes at the same time. For that, you need a cluster-aware file
> system, like GFS2, which uses DLM to coordinate locks.
> Alternatively, you can use clustered LVM LVs as the raw backing device,
> no FS, and have the LVs active on both nodes at the same time. This is
> how we do it.

So just with plain LV and no FS live migration is possible ?

>>>> I stumbled across sfex. It seems to provide an additional layer of security
>>>> concerning access to a shared storage (my lv ?).
>>>> Is it senseful, does anyone have experience with it ?
>>>> Btw: Suse recommends
>>>> (https://www.suse.com/documentation/sle_ha/book_sleha/data/sec_ha_clvm_config.html)
>>>> to create a mirrored lv.
>>>> Is that really necessary/advisable ? My lv's reside on a SAN which is a RAID5
>>>> configuration. I don't see the benefit and the need of a mirrored lv,
>>>> just the disadvantage of wasting disk space. 

What do you think about sfex and mirrored lvm ?



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