Large FOSS filesystems, was Re: [Beowulf] 512 nodes Myrinet cluster Challanges

[Michael Will]

I found reports that hint at that mirroring within LVM does exist but is
unstable.
Also there are reports of 2.6.9 kernel (rhel4,fc4,...) to corrupt data
with software raid1
and lvm on top of that.

Don't trust your data with it unless you did the experiment with a later
version and know
for sure it is safe.

Michael

 

-----Original Message-----
From: Joe Landman [mailto:landman at scalableinformatics.com] 
Sent: Thursday, May 04, 2006 11:55 AM
To: Michael Will
Cc: Dan Stromberg; beowulf at beowulf.org; Robert Latham
Subject: Re: Large FOSS filesystems,was Re: [Beowulf] 512 nodes Myrinet
cluster Challanges

Michael Will wrote:
> The question is:
> 
> Can you use LVM to do mirroring and striping at the same time, or do 
> you need to use software raid1 below LVM for that?

I havent tried this recently.


> When having multiple chassis, the risk is that a chassis goes down and

> that part of a striped LVM can affect the whole filesystem, going 
> offline and if the drives became corrupted for some reason, it can 
> have corrupted all of your data. If you used mirroring between two 
> physical volumes on two enclosures and then stripe across those 
> mirrors, you could mitigate that.

I believe thats what I said.  Make stripes across RAID1 mirrors. AKA
RAID10.  My apologies if I was unclear.

Joe

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