[DRBD-user] Dual primary and LVM

Gionatan Danti g.danti at assyoma.it
Wed Jul 26 16:14:29 CEST 2017

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

Hi all,
I have a possibly naive question about a dual primary setup involving 
LVM devices on top of DRBD.

The main question is: using cLVM or native LVM locking, can I safely use 
a LV block device on the first node, *close it*, and reopen it on the 
second one? No filesystem is involved and no host is expected to 
concurrently use the same LV.

Scenario: two CentOS 7 + DRBD 8.4 nodes with LVs on top of DRBD on top 
of a physical RAID array. Basically, DRBD replicate anything written to 
the specific hardware array.

Goal: having a redundant virtual machine setup, where vms can be live 
migrated between the two hosts.

Current setup: I currently run a single-primary, dual nodes setup, where 
the second host has no access at all to any LV. This setup worked very 
well in the past years, but it forbid using live migration (the 
secondary host has no access to the LV-based vdisk attached to the vms, 
so it is impossible to live migrate the running vms).

I thought to use a dual-primary setup to have the LVs available on 
*both* nodes, using a lock manager to arbitrate access to them.

How do you see such a solution? It is workable? Or would you recommend 
to use a clustered filesystem on top of the dual-primary DRBD device?


Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti at assyoma.it - info at assyoma.it
GPG public key ID: FF5F32A8

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