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cluster LVM

linux-lvm Jordi Prats 3 participants 3 messages Oct 16, 2007 – Oct 17, 2007

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Hi all,
I've been googling for a while but I found nothing about the current limitations of CLVM. Someone told me that you must use just one logical volume for each volume group. Is that true?

Anyone could tell me witch are and if exists any risks of loosing data by using CLVM given certain configuration? There's anything that it's not safe to use, like snapshots, pvmove...?

Many thanks,
Jordi

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Quoted 4 lines · Jordi Prats

Hi all,
I've been googling for a while but I found nothing about the current limitations of CLVM. Someone told me that you must use just one logical volume for each volume group. Is that true?

No, you can have as many LVs in a VG as you like.

Quoted 3 lines

Anyone could tell me witch are and if exists any risks of loosing data by using CLVM given certain configuration? There's anything that it's not safe to use, like snapshots, pvmove...?

Snapshots & pvmove are not currently cluster aware. so if you need to snapshot or move a logical volume it needs to be active on only one node.

If you are sharing data using a filesystem, then you must use a cluster-aware filesystem if it is to be mounted on more than one node at a time. GFS or ocfs2 are just such filesystems.

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Patrick
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Quoted 7 lines · Patrick Caulfield
Quoted 4 lines · Jordi Prats

Hi all,
I've been googling for a while but I found nothing about the current limitations of CLVM. Someone told me that you must use just one logical volume for each volume group. Is that true?

No, you can have as many LVs in a VG as you like.

I think Jordi's referring to the HA-LVM agents in rgmanager, which do (did?) require that each VG contain only a single LV in order to guarantee metadata consistency when a HA-LVM resource is relocated within the cluster.

Regards,
Bryn.

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