On 13 Apr 2003 at 1:51, Paul Ripke wrote:
> Point taken. My definition of a spindle, I suppose, relates more to
> heads. And also becomes dependent on application - specifically I/O
> size. 5 disks in a stripe (RAID0), where the I/Os are small enough to
> only hit single disks, is 5 spindles. If the I/Os are big enough to
> hit more than one disk, it's 1 big spindle. This is where the black
> art tuning of RAID block sizes comes in...

>
> Actually, I'm more interested in reads. And from experience, the
> Sharks RAID block size is small enough that, to Oracle, each RAID5 set
> is a "spindle" in my terminology. That is, 6 heads must move to
> satisfy a read (from memory, the last Shark I had anything to do with
> had 7 disks live in RAID5 with an extra hot spare - 8 disks per set
> total).

Our current TSM server uses Shark storage.  We run a 80gb TSM db on 2
shark raidsets (8 packs) of 18gb drives.  That's 16 spindles.  Each 8-
pack is configured into 1 lun, so the 2 luns show up in aix as 2
hdisks (well, actually 4 with 4 scsi paths, and dpo creating vpath
drives). We pull the vpaths into one volume group and put all of it
into one filesystem.  The logical volume for the filesystem is set
with the "maximum" parm, which alternates pp allocation across the
vpaths.  All 20 db volumes are in this same filesystem along with the
log(5gb), spread across all 18 spindles.

This was designed/setup by a local IBM TSM expert.  It has performed
very well over the years - we are very happy.

Anyway . . .

q)  What is the I/O size of the Oracle db?  It uses 4k pages
internally.  Is the I/O size issued by TSM 4k??

I am getting ready to bring up a new TSM server on EMC Clariion disk
subsystem.  It's default strip depth in a Clariion raid5 is 128k
(128k chunck of data per disk). This is much bigger than the tsm db
size of 4k.   Even dropping down to a 4k strip depth would fit one
I/O per physical disk drive (spindle).

q)  Any idea what the I/O size is that TSM issues for a disk based
staging pool?  I can't find any info about his at all.  I would think
this would be a very large I/O.

Thanks

Rick

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