On May 14, 2007, at 10:25 AM, Ruslan Sivak wrote:
Steve Huff wrote:
If you set up a third box to be the shared storage, doesn't that
now become the single point of failure?
Short answer: maybe. :)
Longer answer: If you set up your shared storage according to
upstream's guidelines, as described in the documentation (http://
mirror.centos.org/centos/4/docs/html/rh-cs-en-4/ch-hardware.html#TB-
HARDWARE-NOSPOF), then you provide at least two channels of
communication between each component in the cluster. In addition,
you choose a platform for shared storage that provides some
redundancy of its own, whether it's multi-controller HW RAID, or
multiple storage nodes on a SAN, or what have you.
CS/GFS operates under the assumption that your shared storage is
fault-tolerant; its job is to make your services fault-tolerant. Is
the recommended "no single point of failure" configuration proof
against your data center burning down, or against a madman with an
axe? Unlikely. Will it allow you to host services in a way that is
considerably more robust and flexible than hosting them on a single
box? Yes.
-Steve
--
If this were played upon a stage now, I could condemn it as an
improbable fiction. - Fabian, Twelfth Night, III,v
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