В Пн., 29/08/2011 в 13:09 -0300, Adriano dos Santos Fernandes пишет: > On 29/08/2011 08:35, Alexander Peshkov wrote: > > В Вс., 28/08/2011 в 19:14 -0300, Adriano dos Santos Fernandes пишет: > >> All, > >> > >> After I bought a new machine, I reinstalled Ubuntu > > 11.04? > > Yes. Kernel is 2.6.38. >
We have same test environments :) Linux fbs 2.6.38-11-generic #48-Ubuntu SMP Fri Jul 29 19:02:55 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux > > >> So I have some questions: > >> > >> Are we doing something wrong? > >> > > In 'man mount' I see: > > Write barriers enforce proper on-disk ordering of journal commits, > > making volatile disk write caches safe to use, at some performance > > penalty. > > > > But if barriers are needed just to make journal commits safe on the disk > > with write cache turned on this seems to be not directly related with > > firebird databases - write cache ON will anyway break firebird database > > in case of crash. Or may be this option actually deals with all data on > > disk, not only journal? > > > > Tested CREATE DATABASE on my old box. To avoid disk fragmentation > > effects database was always created on new shining partition. > > > > writecache=OFF > > ext3 barrier=0 1.084s > > ext3 barrier=1 1.063s > > ext4 barrier=0 3.392s > > ext4 barrier=1 3.380s > > > > As expected - FS ignores barriers when cahce is off. > > > > writecache=ON > > ext3 barrier=0 0.388s > > ext3 barrier=1 1.023s > > ext4 barrier=0 0.410s > > ext4 barrier=1 1.884s > > > > In mode always recommended by us for FB databases, barriers make no > > effect. What is interesting to know - does that fance barriers effect > > only syslog or all filesystem write safety? > > Is this "writecache" you're talking the one changeable by hdparm? > It's switch -W of hdparm :) > Here is another funny time: > > ext4, barrier=1, data=ordered, vmware with file-based disk, guest is > Ubuntu 11.04, host is Windows 7 > create database time: around 0.45s [compared to 2.8s of same config but > non-virtualized] Suppose all caching is done by NTFS. ------------------------------------------------------------------------------ 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
