Re: Migrating from block to lvm

Mike Cave <mcave@xxxxxxx> · Fri, 15 Nov 2019 20:49:56 +0000

Losing a node is not a big deal for us (dual bonded 10G connection to each node).

I’m thinking:

Drain node
Redeploy with Ceph Ansible

It would require much less hands-on time for our group. 

I know the churn on the cluster would be high, which was my only concern.

Mike

Senior Systems Administrator

Research Computing Services Team

University of Victoria

From: Martin Verges <martin.verges@xxxxxxxx>

Date: Friday, November 15, 2019 at 11:52 AM

To: Janne Johansson <icepic.dz@xxxxxxxxx>

Cc: Cave Mike <mcave@xxxxxxx>, ceph-users <ceph-users@xxxxxxxxxxxxxx>

Subject: Re: [ceph-users] Migrating from block to lvm

I would consider doing it host-by-host wise, as you should always be able to handle the complete loss of a node. This would be much faster in the end as you save a lot of time not migrating data back and forth. However this can lead to
 problems if your cluster is not configured according to the hardware performance given.

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Am Fr., 15. Nov. 2019 um 20:46 Uhr schrieb Janne Johansson <icepic.dz@xxxxxxxxx>:

Den fre 15 nov. 2019 kl 19:40 skrev Mike Cave <mcave@xxxxxxx>:

So would you recommend doing an entire node at the same time or per-osd?

You should be able to do it per-OSD (or per-disk in case you run more than one OSD per disk), to minimize data movement over the network, letting other OSDs on the same host take a bit of the load while re-making the disks one by one. You
 can use "ceph osd reweight <number> 0.0" to make the particular OSD release its data but still claim it supplies $crush-weight to the host, meaning the other disks will have to take its data more or less.

Moving data between disks in the same host usually goes lots faster than over the network to other hosts.

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