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multiple compute using single shared storage location

asked 2017-12-18 14:58:44 -0500

jamesopst gravatar image

ive been experimenting with using a single shared fiber channel storage location for multiple compute nodes. I want to ask is this a supported, stable way to use shared storage?

the shared storage filesystem is a ocfs2 filesystem so it supports access by multiple servers simultaneously. I am using Openstack Newton

I changed each compute node /etc/nova/nova.conf instances_path=/mnt/shared_storage/nodes

when I do this two things of interest appear in /mnt/shared_storage/nodes directory a "_base" directory and a "compute_nodes" file.

in the "compute nodes" file I see a listing of all my compute nodes. {"": 1513556772.745646, "": 1513555040.049979, "": 1513554968.764515,.....................

it looks like it is designed to share this shared storage space somehow, right? and to take advantage of _base images uploaded by other computes, right?

I dont see much documentation in this area. so I want to ask is this a supported, stable way to use shared storage? or should I be making a directory for each compute node on the shared storage? thx!

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answered 2017-12-18 17:50:02 -0500

Sharing storage among compute nodes is supported and is, in fact, a popular way of facilitating live migration of instances. When compute nodes share storage, instance disks don't have to be copied to the destination node.

There is an official document that describes how to use NFS to share storage for the purpose of live migration: While I don't know OCFS2, the required steps should be very similar.

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thanks Bernd, nice, we had hoped using shared storage would help us with live-migration. like you say it should! as far as ocfs2, I am not not sure it is stable enough, we have had a few hiccups which seem to be caused by in accessible ocfs2 storage..... thanks for the advice!

jamesopst gravatar imagejamesopst ( 2017-12-21 11:50:04 -0500 )edit

my shared storage medium is via fiberchannel from each node so nfs (ethernet) won't work for me. can anyone recommend a shared filesystem (not ocfs2 and nfs) that can used to share storage between computes nodes? I'm looking thru glusterfs and others but those turn out to be distributed file systems

jamesopst gravatar imagejamesopst ( 2017-12-27 09:54:19 -0500 )edit

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Asked: 2017-12-18 14:58:44 -0500

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Last updated: Dec 18 '17