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Re: To stripe or not to stripe

From: Mark Powell <Mark.Powell_at_eds.com>
Date: 11 Aug 1998 16:05:47 GMT
Message-ID: <01bdc541$bb2ee240$a12c6394@J00679271.ddc.eds.com>


This reply is based on OS level stripping experience.

I think you should consider redoing your design to stripe your data and index across multiple disks. The Oracle binaries are not read heavily and can be spread across the back end of 3 to 6 disks and temp is also a good candidate to spread across disks since many queries will not use it or will use just a few allocations. Believe it or not the same is also true of rbs.

Basically since one disk is for the backup and another is for the application you have five disks to work with. You could stripe the data across three and the indexes across two if you want to keep them separate or because you have a small number of disks you could stripe the entire system across all five disks and go for even I/O distribution which is the real goal of stripping (that is every disk averages the same number of I/O requests per second).

Your current design is not bad, but it leaves you at the mercy of the application in that all your data is on one disk and joins will tend to make disk 4 the bottleneck. Index scans may bottleneck neck 5. If you spread everything including the online redo logs then your chances of experiencing hot disks will be reduced until they are all hot.

When you add more disks you can re-stripe at the OS level and Oracle will not even need to know a change was made, but we prefer to use the datafile rename function to move datafiles.

The main disadvantage with stripping across all 5 available disks is that if one fails then you must recover the entire database; however, there are recovery issues with all designs.

All the above is general and the actual use of your system, OLTP Vs Data Warehouse, number of customers, batch cycles, down windows, etc.... have to go into your design, but in general the more you spread the database the better off you are.

Lisa Lewis <lewis_at_med.pitt.edu> wrote in article <6qp8o5$2kc$1_at_usenet01.srv.cis.pitt.edu>...
> Can anyone tell me whether it is better to separate the indexes and data
> tablespaces on two separate disks or stripe the two disks together and
put
> both the indexes and data tablespaces on the striped set. My intuition
is
> that it is better to not stripe and keep the indexes and data on separate
> disks. I have 7 disks to work with and I planto lay them out as follows:
>
> 1. Oracle S/W
> 2. System TS, Control File 1
> 3. RBS, Control File 2
> 4. Data TS, Control File 3
> 5. Index TS, Temp TS
> 6. Online Redo logs
> Export Dump file destination disk
> 7. Application S/W, Archived redo logs
>
> Any comments suggestions would be greatly appreciated.
>
>
>
Received on Tue Aug 11 1998 - 11:05:47 CDT

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