
Performance |
| Workload |
Tools Reports |
| description |
Workload |
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statistics | characteristics | |
Other |
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requirements: |
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HA, DR etc. |
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| Rules of thumb |
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SAN Fabric |
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| Proposed |
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| configuration |
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Workload from |
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other servers |
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| Modeling with | Adjust config |
| Disk Magic | |
| based on DM | |
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| modeling |
Requirements and |
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expectations met ? | No | |
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| Yes |
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| Finish |
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Figure B-34 Process for sizing external storage
Planning for arrays and DDMs
In general, although it is possible to use 146 GB and 300 GB 10K RPM DDMs, we recommend that you use 73 GB 15K RPM DDMs for iSeries production workloads. The larger, slower drives may be suitable for less I/O intensive work, or for those workloads which do not require critical response times (for example, archived data or data which is high in volume but low in use such as scanned images).
For workloads with critical response times, you may not want to use all the capacity in an array. For 73 GB DDMs you may plan to use about 300 GB capacity per 8 drive array. The remaining capacity could possibly be used for infrequently accessed data. For example, you may have archive data, or some data such as images, which is not accessed regularly, or perhaps FlashCopy target volumes which could use this capacity, but not impact on the I/O per sec on those arrays.
For very high write environments, you may also consider using
Cache
In general, iSeries workloads do not benefit from large cache. Since there is no choice for cache size on DS6000, you should ensure that your workload is not excessively
354DS6000 Series: Concepts and Architecture