Chuck Campbell wrote:
I looked through the list archives, and found one similar question,
but no answers, so I am posting this in hopes of getting some help.
I would gladly read more info if there are some pointers to it.
I would also accept and SGI/irix posting location/mailing list if anyone
knows of one.
My situation:
I have a new raid box, with 2 raid5 sets of 7 x 250Gb disks each.
I need to install it on an SGI (which I have right now, running 6.5.17),
then later move it to a linux server (which is being built in early July.
I need to do proof of concept testing now. The docs indicate this should
not be a problem.
I have set up the raid with a 64k stripe size (the device will see lots
of large files). I assume the device will pass 64kb * 512 bytes per transfer.
I assume I need to use:
sunit = 128, which is 64kb/512b
swidth = 896, which is (#disks-1) * sunit
Sounds about right from my memory.
Is this sane for aligned transfers, or am I misunderstanding something?
I am totally guessing that I should use log section options of
size = 64m
sunit = 128
I do not think you will be able to find an Irix version which
understands aligned logs. If you are going to do a one time
transfer from Irix to Linux then it should be possible to
fix up the superblock and use xfs_repair to reformat the
log to get the stripe alignment setup there. Of course
you need a clean fs before you do this - and note that
Linux and Irix do not understand each others logs - since
the log is in machine byte order, xfs_repair -L will fix
that for you.
As for stripe aligned logs in general, I am not sure that
going for a really large sunit there is a wise move, log
writes are not very big in the first place, the main point
of aligning the log writes was for software raid on linux
which does not like it if you do writes which are not
a multiple of 4K with the way xfs sets up the block
device.
Since this is a hardware raid, you may be as well sticking
with the original log format - especially since this is
your only option on irix.
Steve
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