filecache_max to 8 %

[Aungshuman Paul]

Hi,

The SAP Basis consultant suggest me set the filecache_max to 8 %. When I change it I found it is actually decrease my current value. Now my question is it practical decrease this kernel parameter?

filecache_max (before) 4075143168 Default Imm (auto disabled)
(now) 652023234 8%


Aungshu

[Steven E. Protter · Accepted solution]

Shalom,

Oracle, the database of choice for SAP tends to do better when memory is allocated to its cache, versus the filecache_max.

Other applications on the same system might not be happy with this and their performance might degrade.

Though as a default one of the first things I do during an HP-UX system build is to drop this figure.

SEP

[Emil Velez]

oracle caches its own data in shared memory structures to optimize performance. If the memory is used for file cache then it cannot be used for process memory. Hopefully the SGA sizes for the oracle database is set appropriately high to minimize free unused memory.

[muruganantham raju]

Hello,
The default value of filecache_max is 50%. It is fine to reduct to 10-20% in Oracle systems.
But remember if there are running applications in your system that extensively uses Unified File Cache (UFC) for read/write/mmap calls, then the performance of those applications will be slower. Its better to keep an eye on the memory utilization and application performance.

Regards,
Muru

[Kranti Mahmud]

Hi Paul,

My understanding is that filecache_max is much like the dbc_max_pct of previous HP-UX versions. The usage of memory for file caching can increase up to the max percentage of memory configured (35% in your case). If you ever run into memory pressure, then the usage should decrease as needed to relieve that memory pressure.

Check the man page:

http://docs.hp.com/en/B2355-60130/filecache_max.5.html

Rgds-Kranti