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Former Member
Sep 29, 2009 at 02:59 PM

Reason to size liveCache filesystems 2x RAM?

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Hi,

I am sizing liveCache database for future rollouts of existing system. (liveCache 7.7.04, SCM 5.1, Unix platform)

In the liveCache installation guide, the recommendation is to size the unix sapdata filesystems to be 2x the size of RAM.

SAP SCM 5.1 Standalone Engine SAP liveCache Technology 7.7: UNIX Document version: 1.0 ‒ 08/31/2007

Page 11, section 3.3

File System Name Description Recommendation

/sapdb/<LC_NAME>/sapdata[1-n] Data Volumes 2 x RAM, minimum 3 GB

/sapdb/<LC_NAME>/saplog Log Volume 2 GB

What is reason for this recommendation? I assume it has something to do with the history data in datacache during system shutdown and not also the 1x RAM for KernelDumpFileName path, and > 1x RAM for backup directory because only the liveCache database, not the KernelDumpFileName or backup directories are in the sapdata* filesystems.

In these frugal economic times, we are requested to justify hardware expenditures. 2x RAM seems excessive for sapdata filesystems when the RAM is 200-350GB in addition to the 1x RAM KernelDumpFileName and >1x RAM backup space needed.

Also, I assume it means the total space of all sapdata filesystems is requested to be 2x RAM, and not each individual filesystem.

Is there more explanation, clarification or justification on the disk sizing for liveCache?

Thanks in advance,

Margaret