[linux-lvm] Re: LVM Performance effects?
Michael Heyse
mhk at designassembly.de
Thu Jul 13 15:56:55 UTC 2006
(sorry for disrupting the thread - copied this message from the archives)
> I have set up a file server with LVM on top of RAID 5, and seem to be
> having LVM related performance issue.
Me too.
> raid device: 118.2 MB/s
> lvm device: 49.43 MB/s
> file system: 40.83 MB/s
Have you found an answer to that problem? I couldn't find anything
helpful in the archives. Is this a general LVM on software RAID issue?
I'm measuring a similar performance degradation on my system:
plain Software RAID-5:
# hdparm -t /dev/md3
/dev/md3:
Timing buffered disk reads: 884 MB in 3.00 seconds = 294.49 MB/sec
LVM2 logical volume:
# hdparm -t /dev/data/temp
/dev/data/temp:
Timing buffered disk reads: 316 MB in 3.01 seconds = 105.15 MB/sec
I tried changing the physical extent size, but this has almost no effect.
Some short system information, I'll gladly provide more if needed:
- kernel 2.6.17
- lvm2
LVM version: 2.02.06 (2006-05-12)
Library version: 1.02.07 (2006-05-11)
Driver version: 4.5.0
- 2x dual core xeon, 3 GHz
- 6x WD360GD 36,7 GB SATA Disk
- Software RAID-5 (chunk size: 256kB)
--- Physical volume ---
PV Name /dev/md3
VG Name data
PV Size 167.45 GB / not usable 0
Allocatable yes
PE Size (KByte) 4096
Total PE 42868
Free PE 4468
Allocated PE 38400
--- Volume group ---
VG Name data
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 11
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 6
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 167.45 GB
PE Size 4.00 MB
Total PE 42868
Alloc PE / Size 38400 / 150.00 GB
Free PE / Size 4468 / 17.45 GB
--- Logical volume ---
LV Name /dev/data/temp
VG Name data
LV Write Access read/write
LV Status available
# open 0
LV Size 10.00 GB
Current LE 2560
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:5
Any hints are greatly appreciated.
Thanks,
Michael
More information about the linux-lvm
mailing list