Subject Re: [firebird-support] Upgrade from superclassic to superserver
Author livius
few things:
1. instead FB3.0.3 use recent snapshot. It contain many fixes.
2. look at settings about buffers in your DB itself
if it utilize config then increase DefaultDbCachePages.
Currently you set it to only to 8GB – but db size is much bigger. Is this server to serve only this database or it is also for other things?
If it is only for this database then increase value of DefaultDbCachePages.
If you do only backup on this server without test restore then you can utilize much more RAM.
But i say from Windows perspective not Centos...
3. TempBlockSize you set to only 2MB which is rather small.
I know that you say about 3000 concurrent web users but with this value you will go with sort to the disc quite offten.
You must look if your queries are optimized
and they do not use disk sorting.
You must balance this - use bigger DefaultDbCachePages or bigger sorting cache.
Karol Bieniaszewski
Sent: Tuesday, May 22, 2018 10:58 PM
Subject: [firebird-support] Upgrade from superclassic to superserver


I am in the process of upgrading our Firebird database from 2.5.7 to 3.0.3. While making the upgrade, I want to switch from SuperClassic to SuperServer in order to gain better scalability. However configuring SuperServer i new to me.

Background information:

The database server is a 16 core virtual machine with 128Gb of RAM, and ssd SAN. The database is about 100Gb and growing by 20Gb/year. Daily load is about 3000 concurrent web users. The server is running CentOs 7


Here is the configurations that i have come up with so far. Pagesize is 16K

Firebird config:

DefaultDbCachePages = 524288(8Gb)

On the old server this was 1024. On the new server this value is the one that I am most concerned about, i hope that someone can guide me. I have seen values of up to 2M(32Gb) in other guides, and I tempted to do the same.


FileSystemCacheThreshold = 1048576

The old server used defa ult for 2.5.x


TempCacheLimit = 4294967296

Same as the old server


TempBlockSize = 2097152

Same as the old server


LockMemSize = 9437184

Same as the old server


LockHashSlots = 30011

Same as the old server


Regarding Centos:

Number of open files has been configured to 64K


Reading this Guide: vm.pagecache should be limited to 40-50% However it looks like vm.pagecache is not availabel in CentOs, should  vfs_cache_pressure be used instead?


I hope that someone can point me in the right direction or give some feedback.