Why does cache exceed available physical memory at startup?

Or should I post this on product_futures_discussion? (If the engine is
clever enough to produce this warning, one supposes it could decide on
a lower initial cache

The .DB file exceeds 500MB, the machine has 512MB of RAM but it was
loaded up with PowerBuilder and other stuff at the time.

=====
I. 11/21 13:46:32. Adaptive Server Anywhere Database Engine Version
9.0.2.2451
....
I. 11/21 13:46:32. Running on Windows XP Build 2600 Service Pack 1
I. 11/21 13:46:32. Note: A cache size of 130808K exceeds the available
physical memory of 111788K. A performance penalty may result.
I. 11/21 13:46:32. 130808K of memory used for caching
I. 11/21 13:46:32. Minimum cache size: 2048K, maximum cache size:
307200K
=====

Here is the command line:

"%ASANY9%\win32\dbeng9.exe" -ch 300M -cs -o dbeng9_sniffer_log.txt -os
1M -x tcpip sniffer.db

Breck SpongeBob SmartyPants

--
SQL Anywhere Studio 9 Developer's Guide
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bcarter (AT) risingroad (DOT) com
RisingRoad SQL Anywhere and MobiLink Professional Services
www.risingroad.com

This is just a warning ... it is only an exercise ... had you not been
able to allocate enough (albeit virtual) memory to allocate the
initial cache you would have gotten an error and the server would
fail to start, then!

Why?

Because :

- You have asked it to! (implied 25% of total RAM)
- It can! The OS said we got it when we allocated it!
- There was obviously enough paging file to back that
request up.

all of the above!

This is not a new question at all. Virtual memory OSs are just
like that. Remember this is just the initial status.

We actually have to ask the OS (possibly only with the Windows
OSs) after the fact about how much of it is real hard-core RAM
-- but that status is just a warning and it is definitely transitory

- you could get more real RAM if the database server keeps
enough memory hot

- you can always get less if you load a few more heavy hitting
applications afterwards or another already running application
demands more from the memory manager



"Breck Carter [TeamSybase]" <NOSPAM__bcarter (AT) risingroad (DOT) com> wrote in
message news:m7t1q0hk4s7oivuebdcuvqodiaqol4cvgg (AT) 4ax (DOT) com...