On Wed, Oct 16, 2002 at 12:17:49AM +0200, Ron Arts wrote:
> Hello,
>
> I am interested in performance for hardware/software RAID
> in combination with LVM
>
> So I took a server (Dual Xeon 2.4GHz, 1Gb RAM), a RAID adapter,
> some identical SCSI disks and configured it with several of these
> options (using RH 8.0) and ran a few bonnie++ benchmarks.
>
> Results are below. Anyone care to comment? Especially LVM performance
> disappointed here.
>
> LVM machine setup:
>
> 2 18Gb disks. I created 3 partitions on both disks, 128Mb, 512Mb and 17Gb
> Equal partitions were combined into RAID-1 devices (md driver).
> First md device mounted on /boot, second for swapfile, and third
> as basis for LVM
>
> Out of the volume group four LV were created and mounted as follows:
>
> [root@nbs-126 root]# df
> Filesystem 1K-blocks Used Available Use% Mounted on
> /dev/vg0/root 4225092 1293064 2717400 33% /
> /dev/md0 124323 11517 106387 10% /boot
> /dev/vg0/home 4225092 32828 3977636 1% /home
> none 514996 0 514996 0% /dev/shm
> /dev/vg0/var 4225092 51720 3958744 2% /var
> /dev/vg0/mysql 16513960 32828 15642272 1% /var/lib/mysql
Ron, I don't get your configuration by this df output :(
You've got 3 mirrored MDs on 2 disks (1st: 128Mb, 2nd: 512Mb, 3rd: 17Gb)
3rd is used as the one and only physical volume (say /dev/md2)
for volume group "vg0", right?
How comes that the grand total of /dev/vg0/{root, home, var, mysql}
is ~27.84Gb when the volume group only holds the 17Gb of /dev/md2?
>
> Is there a reason for the performance degradation I saw with LVM?
If my above thoughts are correct, the logical volume(s) used could well be
suffering from bad mapping onto disk(s). You can check the mapping with
either "pvdisplay -v /dev/md2" or for eg. "lvdisplay -v /dev/vg00/root".
I don't feel sure about your MD configuration either.
Hope that spots some light on those numbers which differ from mine
(typically LVM gives a performamce enhancement for sequential input).
The mapping overhead of the LVM1 driver is in the sub percent order.
Regards,
Heinz -- The LVM Guy --
>
> Regards,
> Ron Arts
>
>
> Version 1.02c ------Sequential Output------ --Sequential Input- --Random-
> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
> nbs-126.offic 2008M 24005 99 66015 49 16148 7 27430 98 86915 15 369.0 1 single disk
> nbs-126.offic 2G 23422 99 70919 58 23800 11 25289 86 101485 17 433.4 1 s/w RAID-1
> nbs-126.offic 2G 8152 99 49897 94 23092 27 9122 92 78056 38 331.1 2 s/w RAID-1 + LVM
> nbs-126.offic 4032M 19695 99 44056 42 14179 9 21526 94 86450 16 344.3 1 h/w RAID-1
> nbs-126.offic 4032M 19916 99 24033 22 13343 9 22794 99 111662 30 388.5 1 h/w RAID-5
> ------Sequential Create------ --------Random Create--------
> -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
> files:max:min /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
> nbs-126.office.n 16 2481 99 +++++ +++ +++++ +++ 2424 99 +++++ +++ 5508 98 single disk
> nbs-126.office.n 16 2530 99 +++++ +++ +++++ +++ 2437 99 +++++ +++ 6062 100 s/w RAID-1 soft
> nbs-126.office.n 16 800 99 +++++ +++ 12848 98 807 99 +++++ +++ 2591 99 s/w RAID-1 + LVM
> nbs-126.office.n 16 2138 98 +++++ +++ 31126 98 2200 99 +++++ +++ 5322 98 h/w RAID-1
> nbs-126.office.n 16 2182 99 +++++ +++ 27238 86 2172 98 +++++ +++ 5261 97 h/w RAID-5
>
>
> Notes:
>
> The last two are with hardware RAID (GDT 4513RZ), and 2Gb RAM instead of 1, but I adjusted
> the -s parameter for bonnie++ accordingly.
>
> commandline:
> # ./bonnie++ -d /tmp -s 2048 -x2 -uroot
> Results shown are for the second run. Machines were otherwise inactive, and carried a
> minimum install.
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf
Germany
Mauelshagen@Sistina.com +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
_______________________________________________
linux-lvm mailing list
linux-lvm@sistina.com
http://lists.sistina.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
