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Re: [Linux-cluster] Re: Storage Problems, need some advice



On 11/7/06, Riaan van Niekerk <riaan obsidian co za> wrote:
> After doing much more research I came across the DS300 by IBM. It uses
> SCSI drives, is fully redundant, does iSCSI and doesn't cost an arm
> and a leg (just an arm). My question is, their site says linux
> clustering isn't supported, but does it have to be? Doesn't iSCSI let
> you do the same thing GNBD does?
>

hi David

do you have a link to the page with that statement? "linux clustering"
is somewhat of an ambiguous term. Within the context of Red Hat software
(excluding Linux Virtual Server and high-performance computing
clusters), it can mean either:

a) Cluster Suite (without GFS) - only one node in a cluster accesses the
storage at a time. if you fail/switch over, one node unmounts an FS,
another one mounts it.

b) GFS (which implies/includes Cluster Suite) - multiple nodes accessing
   the same LUN with a (G)FS on top of it

I am not familiar with entry-level iSCSI initiators. I always thought
iSCSI is logically like fibre, e.g. multiple hosts in the same raidgroup
can concurrently access the same LUN/FS. Perhaps these entry-level iSCSI
arrays are more like regular SCSI meaning that they do not support
multiple initiators accessing the same LUN behind a target (storage
processor).

I had a look at EMC cert matrix for the AX100/150 series arrays
http://www.emc.com/interoperability/matrices/AX_Series_SupportMatrix.pdf
thes entry-level EMC iSCSI arrays also only supports non-clustered Linux.

iSCSI will allow you to "do the same thing" as GNDB:
GNDB client and server are replaced iSCSI initiator (Linux host) and
target (dedicated hardware, e.g. EMC array, or software target - not yet
considered production-ready nor included with RHEL). However, if the
hardware has an explicit exclusion of Linux clustering, you are stuck,
not being able to have two nodes aaccess the storage at the same time..

HTH
Riaan

> Also, I talked to someone on their chat who said I could use any U320
> drive with it, basically I could reuse the drives I already have and
> just not use my old enclosure. Does that sound right? Any reason I
> couldn't do that other than loosing all my data?
>
> Anyone using a DS300? Seems like with 15k drives it would be pretty darn
> fast.
>
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> Linux-cluster redhat com
> https://www.redhat.com/mailman/listinfo/linux-cluster


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Here the PDF I was looking at:
http://www-03.ibm.com/servers/storage/disk/ds/pdf/ds300400_interop.pdf

It says it supports Microsoft Clusters so I don't know why it wouldn't
support linux. I also found somewhere else that said more specifically
that it doesn't support RedHat Cluster Manager, but as far as I'm
concerned it has nothing to do with that unless you're talking about
fencing, in which case it would work for me since I'm using power
fencing.

Anyone from RedHat mind chiming in? It's not on the hardware
compatibility list, but there are many things that work that aren't on
that list.


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