On Monday 29 August 2011 at 13:35 Alexander Peshkov wrote: > > Tested CREATE DATABASE on my old box. To avoid disk fragmentation > effects database was always created on new shining partition. >
I've found different results doing a large db restore. ext4 came out better than ext3. I also found ext4 to be better than xfs. The tests were optimised for large files, but I didn't consider barriers. :-( I guess I'll have to go and extend the test suite a bit and report back. > To be politically correct - we should better not recommend people use > ext4 for databases. I'm not so sure. AFAIK, the default for ext4 is barrier=1 and the default for ext3 is barrier=0. In both cases 'data=ordered' is the default. My impression is that ext4 is faster and safer than ext3. But when doing tests it is important to understand what the defaults are. There are defaults set in the kernel and distros can change those defaults. I did some other tests on disc i/o recently and it took me a long while before I discovered the 'sync' option. If ext3 is mounted with the default async then the test results will be meaningless because writes will be cached. I don't know if sync is relevant to ext4. My man8 page for mount (from opensuse 11.3) says sync is only relevant to ext2, ext3, fat, vfat and ufs, but that may just be an error of omission. I also discovered that setting write cache = off at the disc level may not be persistent across reboots. So, to be sure, every test run needs to specify this at the start of the run. Paul -- Paul Reeves http://www.ibphoenix.com Specialists in Firebird support ------------------------------------------------------------------------------ EMC VNX: the world's simplest storage, starting under $10K The only unified storage solution that offers unified management Up to 160% more powerful than alternatives and 25% more efficient. Guaranteed. http://p.sf.net/sfu/emc-vnx-dev2dev Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
