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02906 - 17GB Disk drives
BAL Application Log Documentation BAL Application Log DocumentationThis documentation is copyright by SAP AG.
17GB Disk drives
Crosby
Yes - Of course ... I was talking of the "default"!!!
Cheers
Lloyd R. Perera
iSeries Technology Center
Building 005-2/H103
3605 Highway 52 North
Rochester, MN 55901
LPERERAZU...
Tel: (507) 286-6378 (tieline: 456-6378)
Fax: (507) 253-0424(tieline: 553-0424)
"Crosby Sinclair" <csinclaiZt...> on 08/10/2001 10:06:56 AM
To: sap400Zm..., Lloyd R Perera/Rochester/IBMZIBMUS
cc:
Subject: Re: 17GB Disk drives
Lloyd, one of the way you can prevent the data from going to the larger
drive is after installing new drives you should do a disk balanceing. What
this does is spread out the data on your drive equally to prevent the
overwork of the new drives. The command is STRASPBAL(inV4r4).
Crosby Sinclair
SAP/AS400 System Administrator
Thomson Industries Inc.
Internet www.thomsonind.com
E-mail csinclairZt...
Phone (516) 944-1337
Fax (516) 883-8012
>>> "Lloyd R Perera" <lpereraZu...> 08/10 9:49 AM >>>
"Squash"
I don't think there is any inherent "poor performance" with the higher
density disk drives... If you look at the "phyical characteristics"
including laency, rotation, access speeds etc they will be quite
good...It's just the number of disk arms to meet your disk I/O requirements
that could be the challenge... As usual, I would suggest it DEPENDS on your
specific data volumes and how busy your disk are ... This is where "rules
of thumb" come unstuck... (I agree with Rudi - ultimately it each to
his/her own - like buying a a suit!!!).
For example, if you have 8GB drives and your average arm utilization is
5-8%, then 17GB drives would be a good alternative apprach... but not if
the 8GB drives are all runing at 40% utilization .... I think!!! Keep in
mind however, that the normal distribution of data is generally based on
"space" ... and hence you may find the 17GB drives have a higher
utilization than the 8GB - and more so if the 17GB drives contain the more
recent data - and are accessed more often.
Cheers
Lloyd R. Perera
iSeries Technology Center
Building 005-2/H103
3605 Highway 52 North
Rochester, MN 55901
LPERERAZU...
Tel: (507) 286-6378 (tieline: 456-6378)
Fax: (507) 253-0424(tieline: 553-0424)
Squash <realsquashZy...> on 08/10/2001 08:27:36 AM
To: sap400Zm...
cc:
Subject: 17GB Disk drives
Anyone out there running 17GB drives in a production environment? I know
that IBM says not to,
but the last time we spec'd our systems out, they said to run 4GB drives
because the 9GB's were
too slow for SAP. Well now we have 35 9GB drives and they perform great.
Thanks,
Andy
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