This article states that ReiserFS is particularly good for use on a database server machine, so which is correct? Is there just an issue with SAPDB that causes it to not work well with journaled file systems? I have ran MySQL on the ReiserFS for quite a while without any disk I/O issues at all.
http://www.extremetech.com/article2/0,3973,1160504,00.asp Kevin -----Original Message----- From: Nigel Campbell (DSL AK) [mailto:[EMAIL PROTECTED] Sent: Wednesday, September 10, 2003 8:26 PM To: '[EMAIL PROTECTED]'; Kevin Wilson Subject: FW: Hard disk lit-up like Christmas tree ??? You're better off with ext2 (or raw partitions if you're feeling really keen) for a database. As a generalisation, it isn't a good idea to put databases on a journalling file system for the following reasons: (i) The journalling function is redundant as the database does this anyway. This generates redundant disk traffic. (ii) Journalled file system logs are most definitely not optimised for database access patterns. Databases generate lots of small writes to big files, which create disproportionately large log entries with lots of wasted space (i.e. entire 8k data-base blocks being written by the db and journalled by the filesystem for a single-row change). This wastes a large amount of log space and places a big garbage colleciton burden on the logs. In some journalling filesystsms such as LFS the log entries become the new disk blocks for the filesystem and the old ones are garbage collected - which would aggravate the external fragmentation of the database files. (iii) JFS's don't keep filesystem metadata up-to-date in realtime - typically there is an asynchronous writer process that goes through the log and writes out the changes. On a busy system, this may lead to a lot of journaled-but-not-written changes which are inefficient, particularly if there is is significant locality-of-reference. The logs can also run out of space if a busy system can't keep up with the garbage collection. I've seen an instance of Baan (an also-ran in the ERP racket) being deployed on an HP-UX box with journalling filesystems. This had persistent performance and space problems until someone worked out that they were running the database on a journalled filesystem. After they reformatted the partitions as UFS (berkely FFS) the problems went away. Nigel. -----Original Message----- From: Kevin Wilson [mailto:[EMAIL PROTECTED] Sent: Thursday, 11 September 2003 10:11 a.m. To: Sapdb General List (E-mail) Subject: Hard disk lit-up like Christmas tree ??? [System] SuSE v8.1 w/ using ReiserFS SAPDB v7.3.0.34 Several sapdb processes are in a Uninterruptible Sleep state and kreiserfsd keeps popping in every so often. The hard disk is activity is very high and the database access is slower but still accessible. Any ideas? Kevin "Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety." -Benjamin Franklin, 1759 _______________________________________________ sapdb.general mailing list [EMAIL PROTECTED] http://listserv.sap.com/mailman/listinfo/sapdb.general _______________________________________________ sapdb.general mailing list [EMAIL PROTECTED] http://listserv.sap.com/mailman/listinfo/sapdb.general _______________________________________________ sapdb.general mailing list [EMAIL PROTECTED] http://listserv.sap.com/mailman/listinfo/sapdb.general
