Backing up 20 gig from one client and 20 gig from another client may or may not
be a valid comparison. A client consisting of mostly 20 gig of small files will
encounter significantly more overhead associated with processing directories,
ADSM database entries, and network transmissions than another client with 20 gig
of mostly large files.

Are you using RAID 5 for your disk storage pool? There can be a pretty
significant write penalty that can be partially overcome with fast write cache.

Did you place multiple storage pool volumes on the same physical disk or
intermix them with ADSM database?

You might take a quick look at your performance with vmstat and iostat and
filemon to see where your bottleneck is.




Steve Branch
Phillips Petroleum
e-mail: swbranc AT ppco DOT com





"Cohn, Grant" <Grant.Cohn AT SAPREF DOT COM> on 07/29/99 04:27:05 AM

Any replies will be addressed to: "ADSM: Dist Stor Manager"
      <ADSM-L AT VM.MARIST DOT EDU>


To:   ADSM-L AT VM.MARIST DOT EDU

cc:
(bcc: S W Branch/Sweeny/Phillips Petroleum/us)







 Subject: DISK Storage Pool Performance








Greetings all

I have just tried to use SSA disks as a primary storage pool for one of our
NT clients (running ADSM 3.1.0.7)

1. I created a storage pool with a device class of DISK (Using RS6000 AIX
4.1.5 & ADSM server 3.1.2.20)
2. Formatted 10 1.5 Gb files on the SSA disks using dsmfmt -m -data
xxxxxxxxxxxx 1500
3. Defined these disk storage pools to my storage pool created in 1. above
4. Created a Mgmnt class to use this new storage pool
5. Changed my dsm.opt file on the NT server to use this mgmnt class
6. Ran a first-time incremental backup on one of the drives.

While the backup was executing I noticed that all 10 of my disk storage
volumes were being used at the same time, i.e. they were all filling at the
same time.

Worst of all - this backup took 1h45 mins to backup 2.8 Gb.
To compare, I am backing up 20Gb to tape in 2h10mins on another NT server
connected on the same network.

Anybody with ideas, firstly why it used all 10 volume (disk files) at the
same time, and secondly why the performance is so slow. I would expect disk
storage to be faster.


Many thanks

Grant Cohn
Shell & BP Petroleum Refineries
Prospecton
DURBAN
South Africa.