RE: Determine bottlenecks during backup

It was a 2-way 570 with 16GB RAM and 54 70GB 15K disks.  48 disks in 4
0595s with 2757s and the remaining 6 disks in the CEC with the base RAID
card.

The machine has since been LPARed and had more RAM added to handle the
multiple WAS instances.  I haven't run any more benchmarks as we moved
to BRMS & save-while-active for most stuff so tape performance is mostly
a non-issue now. 

As I recall at COMMON last year IBM noted about 235-250GB/hour as a
potential speed on SCSI-attached LTO3s.  I figure slightly better than
average compression would explain how I'm exceeding what IBM noted.

Speaking of which, what compression are you using?

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: Wednesday, March 01, 2006 12:59 PM
To: Midrange Systems Technical Discussion
Subject: RE: Determine bottlenecks during backup

John,

Quick question, what type of hardware set up do you have that you're
getting 275MB/s with an LTO3 drive connected to a 5702?

Specifically, I'm wondering about CPU/RAM and Disk subsystem.

As I run some test saves on a single rather large library, I'm seeing
average disk usage going from an idle of 1% up to about 20% with a spike
to 40%.  I'm wondering if this is an indication that my disk subsystem
is the bottleneck.  

I know that 40% is a magic number for disk utilization, but for the
purpose of a save I expect disk utilization to be higher if it was the
bottle neck.

Thoughts?

Thanks,


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

> -----Original Message-----
> From: midrange-l-bounces@xxxxxxxxxxxx 
> [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Jones, John (US)
> Sent: Thursday, February 23, 2006 11:35 AM
> To: Midrange Systems Technical Discussion
> Subject: RE: Determine bottlenecks during backup
> 
> 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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