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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