[Lustre-discuss] Inquiry and advice requested on Lustre Implementation

[Brian J. Murrell]

On Thu, 2009-02-12 at 11:15 -0500, PMilanese at nypl.org wrote:
> Greetings-

Hi,

> I would consider going commodity for our next generation, with smaller
> and numerous nodes. After looking into the Lustre documentation, I do
> see it as a good test candidate. However, we would like to have our
> OSS's and OST's on the same hardware.

Just to make sure that nomenclature is not being confused, and OSS is a
computer.  and OST is a storage target (i.e. disk) the OST stores Lustre
objects (files and portions of files) on.

An OST can be an externally connected (logical) disk such as a DDN LUN
connected by fibre channel to the OSS.  An OST can also be connected
internally in the OSS such as a SATA, SCSI, (or heaven forbid) and IDE
disk.

Am I to understand you want the latter?  Do you already have this
hardware configuration and you just want to (re-)deploy it with Lustre?

The reason being, is that Lustre can only achieve it's HA
deliver-ability goals when two OSSes (or MDSes) can see a common storage
target.  Doing this with internally connected disks is difficult and
usually requires a replication technology like DRBD to ensure that the
(i.e. network mirrored) disks are in sync.  This is a Sun-unsupported
configuration, but there have been reports of success on this list.

> This being said, can someone pinpoint me to a possibly high level
> diagram of how redundancy can be implemented across nodes, if
> possible?

I don't know of any diagrams, but typically, you connect redundant OSSes
to dual-ported disks so that either OSS can serve it's data.  When one
dies, the other takes over.

b.

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