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Re: [Linux-cluster] DDRAID vs. GNBD+MD



On a related node, was DDRAID ever stabilised

In fact, it's been removed from CVS:

http://sources.redhat.com/cgi-bin/cvsweb.cgi/cluster/ddraid/Attic/?cvsroot=cluster

Ouch. I don't suppose that means that there is a reasonable alternative to
it? I know DRBD works for providing RAID1 without cantralized storage, but
is there anything supported and available that can provide any other kind
of RAID?

Not that I'm aware of.

I think your best bet at distributed storage is a distributed cluster
file system, a la GlusterFS, Petal/Frangipani (non-Free :( ), Lustre,
etc.

The problem with GlusterFS is that the most it seems to provide is mirroring (RAID1). Lustre supports only striping (RAID0) but the recommendation is to run it on DRBD which provides mirroring (RAID1).

DDRAID at least provided n+1, which although not n+m at least seems to have been a step in the right direction. I am stunned that all these supposed petabyte file systems only support mirroring for redundancy. It really does not follow that an entity that can afford a petabyte of disks can also afford two petabytes of disks to achieve redundancy that doesn't even prevent data loss in case of failure of two speciffic disks.

Gordan


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