[Beowulf] Big storage

Jakob Oestergaard jakob at unthought.net
Fri Aug 24 01:53:42 PDT 2007

On Thu, Aug 23, 2007 at 11:02:28AM -0400, Jeff Blasius wrote:
> Hello Jakob,
> A couple of things...
> 1. ClusterFS has an easy to understand calculation on why raid 6 is
> necessary for the amount of disks you're considering. You do need to
> plan for multi-disk failure, especially with the rebuild time of 1TB
> disks.
> http://manual.lustre.org/manual/LustreManual16_HTML/DynamicHTML-10-1.html#wp1037512

As Greg pointed out, if I can live with isolated filesystems (many small RAID
sets), there's a lot of problems with very big arrays that won't affect this

That said, RAID 6 is probably very interesting to consider anyway.

> 2. Avoid tape if you can. At this scale, the administrative time and
> costs far outweigh the benefits. Of course if you need to move your
> data to a secure vault that's another thing. If you really want to do
> tape, some people choose to do disk > disk > tape. This eliminates the
> read interrupts on the primary storage and provides some added
> redundancy.

So far I've been surprised at the number of people who (mainly privately) has
told me to stay away from tape - that was unexpected, but interesting
nonetheless :)

> 3. We do use Nexsan's satabeasts for storage similar to this. Without
> commenting on costs, the jackrabbit is technologically superior.

Thanks a lot for the comments!


 / jakob

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