On Fri, Oct 18, 2002 at 03:34:23AM -0500, Chien-Yu Chen wrote: > Hi! > I am trying to set up a raid 1 configuration... > I have 2 identical disk, both on primary IDE without any slave device.. > After I set up raid 1, I am having some performance issue.. > > when I write a big file (maybe 20M), it'll pause for a few seconds once in > a while while writing the file...untaring the kernel source is even worse.. > the time it takes to untar is a lot more than twice of untar time on the > same disk with no raid 1 setup... > > can anyone tell me some performance enhancement I can do? thanks
i've seen this on recent hardware and it was only really fixed by kernel support for the IDE chipset--do you have a specifically supported IDE chipset? (eg intel PIIX, non-generic IDE chipset support is what i'm talking about) sadly, there was no amount of tuning in the bios and with hdparm that helped, but those two would be my first stop unless you have a ServerWorks CSB5 chipset in which case, go for kernel 2.4.19 and the latest bios. second, maybe some of the ide-related paramters to the kernel (passable via lilo/grub/whatever) such as idebus=XX (that's probably not the one you want, actually, but you should plumb the readme files, i don't use any of the extended options on machines i have access to..) i assume you tested both disks in non-raid mode or have non-raid partitions on them to verify that it's not a cable problem? changing cables helped the situation on that serverworks chipset a bit--went from taking 15 minutes to boot to about 10, but that was ridiculous on dual pIII-1.13Ghz/4GBram machines nonetheless (we had / raid1'd). and you've done good on the both masters/noslaves, altho adding slaves to my home machine that has raid1 over the two masters in heavy use did not degrade the performance at all (it is as fast as one of the disks alone, using s/w raid1, according to bonnie, under 2.4.16+susepatches, and was about the same under redhat/2.2 on ext2) you should take a look at /proc/mdstat and see if the raid is synced or not-- rebuilding will slow things down as it does at least 100k/s of rebuilding regardless of how busy the system is. you may want to turn down the constant "speed_limit_max" in the kernel sources [.../drivers/md/md.c] (supposed to be sysctl'able but i didn't notice that when i was mucking last time)--our rebuild was happening at about 500k/s even while the system took a full 3 minutes to start sshd and we finally throttled it to 10k/s (min and max) so that we could actually log in before the end of time. that was obviously not the true solution but they were paying me by the hour and i felt bad about taking up so much time twiddling my thumbs waiting for a login prompt.. luck++; raid1 is nifty and works well once you get all the settings resolved. i use it on a middling-busy webserver, my home fileserver/ firewall, and on my colo machine, and have never had a real problem. strangely, the 36G mirror on my home pII-300 running at 33mhz ide bus speed rebuilds faster than the other two (20G mirrors on more recent hardware), but it does rebuild a lot since i have flaky power here so maybe i just noticed the times it happened to not have a lot of resouce contention. _______________________________________________ Siglinux mailing list [EMAIL PROTECTED] http://www.utacm.org/mailman/listinfo/siglinux
