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MaxDB on Windows: Allocation Unit Size for Data- and Log-Files

Hello everybody,

the SAP notes

1173395 - FAQ: MaxDB Konfiguration

993848 - Direct I/O Mount Optionen für liveCache/MaxDB

talk about different Storage-Vendors and mount-options for Linux/Unix.

But does anybody know if there are special recommandations on Windows for the NTFS Allocation Unit Size for the MaxDB-Data and Log-Files?

Thank you!

Rossi

replied

Hi Rossi,

no for Windows there aren't any special recommendations, you may well just stay with the NTFS default cluster size of 4K.

In the worst case scenario this means that for a single 8K access two physical IO operations would be necessary.

But in fact, most often the data volume files are allocated in a few rather large contiguous chunks in the file system.

Therefore don't bother with that!

Nevertheless, under certain conditions it might become an advantage to use a 8K cluster size for the file system where you put the data volume files to.

E.g. if you're using a BI system with MaxDB and therefore using the clustering feature a lot.

But until now (approx. 6 years at MaxDB support) I never came across a single case where the cluster size for the NTFS file system would have been the root cause for problems.

regards,

Lars

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