[ClusterLabs] Antw: Re: principal questions to a two-node cluster

Lentes, Bernd bernd.lentes at helmholtz-muenchen.de
Wed Apr 22 10:17:57 EDT 2015


ok. I've been asked for more precise information. Here they are:

I'd like to create a two-node cluster with a SAN. I have two nodes (HP ProLiant with SLES 11 SP3 64bit) and a HP FC SAN. My ressources are some vm's. Also some databases and web applications. Maybe I will install the databases and applications also into vm's, I don't know currently exactly.
I'd like to have availability, no active/active or master/slave. Active/passive should be sufficient

What I'd like to know:

- If I will use logical volumes, do I need cLVM ? Or is "normal" LVM sufficient ?
- snapshots with cLVM now seems to work: https://www.suse.com/releasenotes/x86_64/SLE-HA/11-SP3/#id303161 (I will use SLES 11 SP3)
- I'd like to have snapshots. Freezing systems before applying software or changing configuration is fine. How can I achieve it ? I don't like to use btrfs on production systems. Ext4 snapshots are experimental. OCFS2 has file snapshots. But most of you propose not use OCFS2. cLVM offers snapshots. Any other idea ?
- How is the setup with cLVM ? This is my idea:  SAN offers one or more volumes to the nodes ==> disks which appears in the nodes from the SAN are used as physical volumes ==> physical volume/s are combined to a volume group ==> logical volumes are created on top of this vg, one lv for every virtual machine ==> formatted with a file system like ext3 (because each virtual machine does not run concurrently on both nodes this should work) ==> each virtual machine in a raw file, one vm for each lv . Does that work ? Possible to run different virtual machines on different nodes concurrently (as a poor load balancing) ?

Thanks for every hint.


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