On Sun, Oct 19, 2003, Maxim K. wrote about "filesystem for database box": > after short consultation, i have come to this conclusion about which > filesystem i should use on my database box (or server) > the winner is: ex2 linux extended filesystem, yes, lassies & lads > > - "why not ext3/Reiser's ?" > - "because journalling is already implemented in the DBMS." > - "why not jfs then ? > - "it is too young, my friends + journalling..." > - "why not xfs , it is so ... juicy ? > - "it is too resource demanding (i have p2 670MHz + 256 MB )" > > if somebody thinks otherwise, please tell me why! > thank you.
Well, some sort of journally may be implemented by the database system, but think of this: your server reboots unexpectedly. Your 100 GB ext2 filesystem becomes "dirty", and the next reboot takes 30 minutes (I'm just making this number up - do your own measurements). After these 30 minutes are over, your database finally has a chance to rerun your journal... Journalling file systems like ext3 will prevent the need for file system checks on boot. If you database has very specific access patterns to the filesystem (e.g., it never creates new files or enlarges existing files) you might be able to patch ext2 to prevent those checks too, but this will not be trivial. Very sophisticated database systems can probably access the disk directly with minimal OS intervention and will not need a journaling file system, but I don't know anything about that. The bootup filesystem tests are especially problematic for "appliances" (which are supposed to be working seconds after the appliance is turned on) and for servers that are supposed to have high-availability. Of course, ext3 might be slower than ext2. You'll need to make those measurements yourself and see if that actually bothers you. Paying a bit more for faster CPUs and disks might be worthwhile to get the benefits of a journaling filessystem. -- Nadav Har'El | Sunday, Oct 19 2003, 23 Tishri 5764 [EMAIL PROTECTED] |----------------------------------------- Phone: +972-53-790466, ICQ 13349191 |Snowflakes are very fragile, but look http://nadav.harel.org.il |what they can do when they stick together! ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
