Hi, I just upgraded a webserver (serving a pretty busy site) from a Dual Xeon 2.4Ghz with a 3Ware 7850 8-port (8x Seagate 120GB IDE drives in RAID5) running FreeBSD 4.11 to a Dual Opteron 248 with a 3Ware 9550SX-8LP (8x Hitachi SATA2 250GB drives in a RAID5) running FreeBSD 6.1-Stable. The site runs considerably slower on the faster machine running 6.1, things seem to be blocking on IO a lot more. For instance a page could load very quickly from Apache, and if you reload straight away it can take up to 20 seconds for the page to load again. When this happens it seems a lot of Apache processes get stuck in the UFS state (in top). Is there a way to debug what's going on? or work around it. It should be much much faster which the faster disks and raid controller. Is this lock contention in VFS? Thanks! Phil
Philip Murray wrote:> When this happens it seems a lot of Apache processes get stuck in the > UFS state (in top).I've seen this when there's a huge directory involved, such as created by a runaway web cache function, PHP sessions, or "PHP accelerator" that creates a lot of small cache files. If so, you'll probably need to delete that directory completely and make sure it doesn't happen again (e.g. use a multi-stage directory tree instead of a big one). You might have luck with increasing dirhash size (vfs.ufs.dirhash_maxmem).