On Fri, Oct 26, 2001 at 01:06:56AM -0600, Andreas Dilger wrote: > On Oct 26, 2001 00:03 -0500, Robert Macaulay wrote: > > I realized I didn't include a lvdisplay -v of my volume. Here it is. > > The disks are spread out over 4 scsi busses. > > > > --- Logical volume --- > > LV Name /dev/vgOracle/foo > > VG Name vgOracle > > LV Write Access read/write > > LV Status available > > LV # 52 > > # open 0 > > LV Size 9.04 GB > > Current LE 2314 > > Allocated LE 2314 > > Stripes 26 > > Stripe size (KByte) 64 > > Allocation next free > > Read ahead sectors 120 > > Block device 58:51 > > Well, there was a patch in 2.4.13 to the LVM code to change the readahead > code. Andreas, to what patch are your reffering to. Still see the per major read_ahead code in 2.4.13 which is partially usefull in the best case. Heinz > First off, it makes the default readahead 1024 sectors (512kB) > which may be the maximum SCSI request size (don't know the details > exactly). It also sets a global read_ahead array, so this may impact > it also. See above, you have a "read ahead" that is smaller than a > single stripe, so it isn't really doing you much good. > > However, it is also possible that striping across 26 disks is kind of > pointless, especially for Oracle. You are far better off to do some > intelligent allocation of the disks depending on known usage patterns > (e.g. put tables and their indexes on separate disks, put rollback > files on separate disks, put heavily used tables on their own disks, > put temporary tablespaces on their own disks). > > With LVM, you can easily monitor which PVs/PEs are busiest, and even out > the I/O load by moving LVs/PEs with pvmove (although you CANNOT do this > while the database is active). > > Make sure you keep backups of your LVM metadata (both vgcfgbackup, and > also save the text output of "pvdata -avP" and "lvdisplay -v"). > > Cheers, Andreas > -- > Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto, > \ would they cancel out, leaving him still hungry?" > http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert > > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Sistina Software Inc. Senior Consultant/Developer Am Sonnenhang 11 56242 Marienrachdorf Germany Mauelshagen@Sistina.com +49 2626 141200 FAX 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
