questions on tuning PE for linux and SAN on linux..

jason andrade jason at dstc.edu.au
Mon Mar 25 07:56:00 CST 2002


On Mon, 25 Mar 2002, Gabor Kovacs wrote:


please note i don't speak for dell or even pretend to have a clue
about their linux plans.. but..

> This sounds a little bit crazy :)

you're telling me..  it was hard enough getting dell to sell me the
kit in the first place when i told them i was putting linux and not
windows on it.. but i won't get into that.

> We bougt several months ago a SAN environment too. (We have a PV660 and
> a 51F Switch now with 1550, 2550 and 4400 machines.) We planed use NFS
> and SAN in a mixed Linux and Windows environment. Dell said the support
> for SAN on Linux will we available in the 1st quarter of 2002, but I
> think nothing was happened there.

can you tell me anything about your PV660 ?  i'm quite curious to know
what sort of box it is, since it seems to fit firmly in no man's land
(650 was Clariion and the 4500/4700 is EMC/Clariion - who made the
660?).  how do you manage it ?  is it windows management based or?

> See above :) Is there any plan when will be SAN available for Linux?

from what i understand you can run Linux in a SAN right now, but you
cannot run multiple linux boxes with access to the SAME luns because
software like SANergy (Tivoli's stuff?) isn't available, which means
if you have multiple machines accessing (even just reading) the
same LUN, it can lead to data corruption (worst case, presumably
only on multiple machines mounting read/write) or a machine crashing
with filesystem caching/metadata issues.

> I don't really understand You.
> If I'm right it means that there is problems with ext2 or what? And how
> comes megaraid here? :)

i think he was just giving the pointers into the article - i don't think
it's specifically a ext2 or megaraid issue.

> Why is this better than NFS. No. Sorry :) Bad question.
> Why is this working and NFS not in SAN environments?

there appears to be nothing available (apart from sistina/GFS) which handles
intra filesystem locking in a Linux SAN

it's most annoying.  i was really looking forward to being able to
decouple storage from applications - now i have to architect something
more complex (and still involving NFS).  NFS is quite a lot of overhead
when you are trying to push 1T/day over it.. 

hmm, meeting Dell tomorrow to talk about these and other issues... might be
time to get some sleep.

cheers,
-jason




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