Subject Re: [firebird-support] Re: Issue with Database Cache Size on FB 3.0

Something funny is going on regarding the memory consumption, I have attached screenshots showing the memory counters. If you look at the process itself (file TaskManager_Process_Firebird_Only_Consumed_2GB.jpg), it only consumed 2 GB. If you look at Windows Task Manager (file TaskManager_Performance_ALL_RAM_Consumed.jpg), where it says "Physical Memory, just under the memory graph where it shows 3.13 GB used, the cached memory is 29963 Mb. I know Firebird is who consumed that CACHED memory because I am forcing the DB to read 70GB on purpouse, but why is the memory not showing under the process Firebird ? (it only shows 2GB used there).

My aim is to set the config to only use RAM (no file system cache), and to place the hole DB in RAM for caching when reading, I am struggling to find a config mix that will do that. The config variables are:

FileSystemCacheThreshold = 0
FileSystemCacheSize = 80
TempCacheLimit = 24576M (I am not sure what this value is for, it seems to mean the maximum amount of temporary things to have in memory, like DB read cache)

The above 3 variables are the ones I am playing with, plus the DefaultDBCachePages = 90000 in Databases.conf


----- Original Message -----
From: Dmitry Yemanov dimitr@... [firebird-support]
Sent: Wednesday, June 01, 2016 3:49 PM
Subject: [firebird-support] Re: Issue with Database Cache Size on FB 3.0

01.06.2016 04:16, Fabian Ernesto Chocron wrote:
> We are having trouble setting up the database cache size on FB 3.0
> running on Windows 2008 R2 64 bits with 32 GB ram.
> The problem we have is we cannot get the server to allocate the ram for
> the cache as we intend. With FB 2.54 we had the DB cache set very high,
> close to 1 GB per database, all running in RAM memory. With FB 3.0 we
> read it can allocate much more RAM to the cache, but it appears the
> server is allocating very small amount of Ram when the first user
> connects to the DB, and as we connect more users to the DB the ram
> consumption increases slowly.

What memory counters do you look at? Virtual (reserved) memory usage
should grow high with the first connect, physical (committed) memory
usage should grow together with your load, while pages are being read
from disk.

> On firebird.conf
> FileSystemCacheThreshold = 0
> FileSystemCacheSize = 17179869184 (this is 16 GB - the server has 32 GB
> ram.)

These changes conflict with each other. You disable filesystem cache
with the first line and still want to use 16GB with the second line.

> On databases.conf
> MyTestDB = c:\Temp\MyDb.fdb
> {
> DefaultDbCachePages = 458752
> }

First of all, I'd suggest to reset FileSystemCacheSize back to zero and
set FileSystemCacheThreshold to something higher than 458752 pages (e.g.
500000). Then re-test your memory usage and only then start tweaking the
filesystem cache.

BTW, don't you occasionally have page cache override at the database
level? What is gstat -h output?





Visit and click the Documentation item
on the main (top) menu. Try FAQ and other links from the left-side menu there.

Also search the knowledgebases at


Yahoo Groups Links

[Non-text portions of this message have been removed]