[Beowulf] Big storage

Loic Tortay tortay at cc.in2p3.fr
Thu Sep 6 03:32:39 PDT 2007

According to Leif Nixon:
> > Even if we hadn't been close to a scheduled downtime, the applications
> > running on most of our X4500 are fault tolerant enough that we can
> > offline a machine for some time without a significant impact.
> These are dCache pools? If so, have you seen any dCache specific
> issues? You symlink the control directory to a non-ZFS filesystem?
Most of the X4500 we have are indeed dCache disk pools.

We had an issue with the (incredibly) long dCache startup time due to
some strange problem in Java/ZFS metadata interaction.

Our solution was indeed to move the dCache metadata to a UFS filesystem
on the mirrored system disks.

This issue and probably a few others were mentionned during the
X4500/ZFS related presentations during last HEPiX meeting in Hamburg.
I remember seing you there (or someone wearing a badge with your name
on it :-).

Specifically, Robert Petkus's presentation on disk systems tests (with
small input from me) and Martin Gasthuber's presentation on ZFS usage
at DESY and IN2P3 Computing Centre (for which I provided some data).

| Loïc Tortay <tortay at cc.in2p3.fr> -     IN2P3 Computing Centre     |

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