[Pvfs2-users] Can PVFS over multiple disks on a single node tolerate disk failures?

Scully hxsrmeng at gmail.com
Fri Jan 18 17:44:57 EST 2008


That's really a wonderful answer. Thank Sam.

Let me ask another question. Since the system I just mentioned will not
tolerate disk failure, I will try "Installing PVFS2 on a cluster". Say, I
have several nodes, I use one disk for PVFS2 data on each.

Dose such a system tolerate node or server failure? Is there anyway to
configure it to achieve this, if one node fails, the application still can
get files from other nodes? If it can, how many nodes I have to have at
least?

Thank you.



On Fri, 2008-01-18 at 15:59 -0600, Sam Lang wrote:

On Jan 18, 2008, at 2:29 PM, Scully wrote:

> I want to store PVFS data on four disks in the same node. If I don't
> choose RAID, based on my understanding to <3.2 How can I store PVFS
> data on multiple disks on a single node?> in the FAQ, I should set
> four servers, each for a disk.
>
> Can such a system tolerate disk failures?

It would be similar to RAID0 over those disks.  There's no mirroring
or data redundancy, so a disk failure would cause a loss of data.

> Should I set each disk a metadate server to get the disk failure
> tolerance?

In your case adding metadata servers won't help, since all the servers
are running on the same node.  Just pick one of the disks (servers) to
manage the metadata.

>
>
> I think the <7.3 Can PVFS tolerate disk failures?> in the FAQ means,
> if I use RAID5 or RAID6 to combine the disks first, then, it can
> tolerate, am I right?

Yes.  redundant RAID schemes provide for recovery if a disk should
fail.  Running PVFS servers on-top of RAID5 usually slows down writes
a little, but if you want to tolerate failures, the performance hit is
probably worth it.
-sam

>
>
> Thank you.
>
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