RAID requirement with block storage

asked 2014-01-03 07:34:58 -0500

anonymous user


updated 2014-01-22 15:12:55 -0500

Evgeny gravatar image

Hi ,

I have read that there is no need for RAID with block storage. But if hard disk fail on the storage ,how can we recover our data?

Also what is the advantages of using Fiber channel between compute and storage ?

Where will be data stored when we create any instance ? Will it reside on compute node or block storage?

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answered 2014-01-03 08:22:55 -0500

SamYaple gravatar image

Question 1:

Raid is not needed for _distributed_ storage. You would still need traditional methods to preserve data if you are using LVM or NFS as a cinder backend.

Ceph is an example of a distributed storage backed for Cinder (block devices). You would not want to use raid with ceph.

Swifts object storage is another example of a distributed storage system where using raid actually decreases performance in some cases while no giving any benefit.

To sum up very briefly, if you are using a distributed storage backend, you don't use raid. If you are not, then you can use raid.

Question 2:

Not my area of expertise. Ill leave that to someone else.

Question 3-4:

This depends on how you configure things. It can be ephemeral existing only on the compute node while that instance is alive; it can also be persistent and be attached and detached from many instances.

It is all in how you configure the system.

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Asked: 2014-01-03 07:34:58 -0500

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Last updated: Jan 03 '14