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Asset ID: 1-71-1010176.1
Update Date:2009-09-27
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Solution Type  Technical Instruction Sure

Solution  1010176.1 :   Rules for SAP on Sun disk layouts  


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  • Sun Enterprise 3500 Server
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  • GCS>Sun Microsystems>Servers>Midrange Servers
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PreviouslyPublishedAs
213981


Steps to Follow

Rules for SAP on Sun disk layouts

Preface

This document is provided to as an aid to avoid disk layout errors on SAP R/3 on Sun Solaris[TM] systems.

General Rules

  • Separate database logs from the other database storage

  • For database logs, getting write complete confirmation from the disks as fast as possible is essential.

  • For the sapdatas, use a simple disk layout that is easy to understand and can be extended without big performance loss. Never fill the disks more than about 70% so there is room for extending space and time for ordering new disks/disk subsystems.

Simple Database Log Rules

  • Place database logs on separate disks that contain no other data.

  • Make sure the remaining disk space of the disks containing the database logs will remain empty or contains disk space with little activity. The best way to achieve this is by placing (one or more) empty, read-only mounted file systems on those disks. Leaving those disks mainly unused is no waste of money - a slow R/3 system is much more expensive than buying some disks. Another way to avoid that database log disks are used for other purposes is to use solid state disk - they should be chosen to have about the same size as the database logs.

  • Place each log filesystem or raw device only in the outer areas of the disks. To do this, allocate space for the logs first. On empty disks the outer cylinders are used first.

  • Never place two consecutive logs (e.g. origlogA, origlogB or mirrlogD, mirrlogA) on the same disk(s) because during log switch time, the old logs are copied to the archive directory while the new logs are already used for the next transactions.

  • For large size R/3 installations, place database logs only on disk subsystems with write cache (e.g. A1xxx, A35xx, T3xx), or on solid state disks, or use the Fast Write Cache option. In these cases, striping is normally not necessary. However, note that there may be restrictions if the database server is part of a cluster. Place the disks containing the database logs in a separate access path (separate controller, at least separate loop). If there are only disk subsystems available without write cache, stripe the logs over 4 or better more disks. Make sure the disks containing the database logs will never be used for other data.

  • For medium size R/3 installations, placing database logs on separate write cached disk subsystems may not be necessary, depending on the I/O write load. As always, place the logs on separate disks and at least stripe the database logs (use RAID 0) if they have to be placed on disk subsystems without write cache.

  • For Oracle, use Oracle log mirroring as recommended by Oracle. You normally do not need Volume Manager mirroring for the Oracle logs



Product
Sun Enterprise 3500 Server

Internal Comments

None.


Previously Published As
23975

Change History
Date: 2003-05-20
User Name: Administrator
Action: Migration from KMSCreator
Comment: updated by : James Verlee
comment : No comment
date : Feb 8, 2002



updated by : James Verlee
comment : Updated version,spell check, per Knowledge Initiative Program.

date : Feb 4, 2002



updated by : Bernd Finger
comment : No comment
date : May 4, 2001



updated by : Bernd Finger
comment : Document reviewed for issuing as an external infodoc.
date : May 4, 2001



updated by : Wendy Bean
comment : Issued per request of Charles Price.
date : May 4, 2001



updated by : Thom Chumley
comment : No comment
date : Nov 9, 2000



updated by : Bernd Finger
comment : clarified usage of database log disks.
date : Oct 12, 2000



updated by : Bernd Finger
comment : This document is ready to be submitted. It includes
changes made after responses from Bob Sneed
and Bob Larson regarding a previous version of this
document.
date : Oct 11, 2000



updated by : Bernd Finger
comment : Article created.
date : Oct 10, 2000



updated by : Bernd Finger
comment : Article changed.
date : Oct 10, 2000
Version: 0
Product_uuid
29b720d2-0a18-11d6-9865-e60ab6457390|Sun Enterprise 3500 Server

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