RE: Determine bottlenecks during backup -- MIDRANGE-L

What kind of tape drive?

The SCSI interface in this case is very likely not the bottleneck; I've
got 5702s that are doing about 275MB/s (compressed) with LTO3 drives.
That leaves the potential bottlenecks as:

1. Tape drive.  If LTO2 or LTO3, this should not be the bottleneck
unless the drive is malfunctioning or dirty.
2. System bus.  Could be the problem.  Where is bus 28?  If not in the
CEC, what type of tower?  I had LTO2 drives on our former 830; one on a
controller in the CEC and one in a migration tower (a former 720 frame).
The drive on the controller in the CEC was significantly faster (more
than 2x) than the drive in the tower even though the drives themselves
were identical.
3. System (CPU/RAM).  This is probably not the bottleneck unless the
partition is RAM-constrained.
4. Disk subsystem.
5. Object type.  Fewer-but-larger objects will save faster than lots of
small objects.  The more objects there are the higher the system
overhead.
6. Save type.  Turn on compression for the non-SAVSYS pieces; you've got
plenty of CPU to handle it.

Also, try to figure out which part of the 21 is taking a lot of time.
Is it IFS, NONSYS, SAVSYS, etc.?  Easiest way is to look at the job log
afterwards and look at the timestamps.

John A. Jones, CISSP
Americas Information Security Officer
Jones Lang LaSalle, Inc.
V: +1-630-455-2787 F: +1-312-601-1782
john.jones@xxxxxxxxxx

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Wilt, Charles
Sent: Thursday, February 23, 2006 10:02 AM
To: Midrange Systems Technical Discussion
Subject: Determine bottlenecks during backup

All,

I'm trying to evaluate the performance of our new backup system.

The tape device is rated at 200 MB/s and is attached to an 160MB/s 5702
SCSI card.

However, on my first test save menu option 21 save I saved 238.7 GB of
data (uncompressed) in about 90 minutes, a throughput of about 45 MB/s.

The iSeries is a model 810 with 2700CPW of which 87% (2349CPW) is
assigned to the primary partition being backed up.

System bus 1 has a 2757 Controller card with 12x4326 RAIDed.  Of those
12 disks, the system ASP contains 10 disks, and a user ASP is configured
with 2 disks.

System bus 28 has the 5702 controller card.


How can I tell if the save is bottlenecked by CPU, disk, bus, or tape
device?

Thanks,

Charles Wilt
--
iSeries Systems Administrator / Developer Mitsubishi Electric Automotive
America
ph: 513-573-4343
fax: 513-398-1121
 

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