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Archive for January, 2010

Linux Software RAID10 Benchmarks

January 31st, 2010 1 comment

Tests are done across four 7200RPM SATAII drives on a PCI-X card sitting on a PCI (32-bit, 133MB/sec theoretical max) bus, probably the slowest bus configuration possible, and then again after being moved to a motherboard with dual PCI-X slots. Server is running Ubuntu 9.10 AMD64 Server.

Benchmark is a simple ‘dd’ sequential read and write.

write: dd if=/dev/zero of=/dev/md2 bs=1M
read: dd if=/dev/md2 of=/dev/null bs=1M

mdadm –create /dev/md2 –verbose –level=10 –layout=n2 –raid-devices=4 /dev/sd[ftlm]1

PCI PCI-X
write: 13.2 MB/s 144 MB/s
read: 4.0 MB/s 89.3 MB/s

mdadm –create /dev/md2 –verbose –level=10 –layout=f2 –raid-devices=4 /dev/sd[ftlm]1

PCI PCI-X
write: 48.3 MB/s 131 MB/s
read: 92.7 MB/s 138 MB/s

mdadm –create /dev/md2 –verbose –level=10 –layout=o2 –raid-devices=4 /dev/sd[ftlm]1

PCI PCI-X
write: 47.4 MB/s 135 MB/s
read: 98.7 MB/s 142 MB/s

And more comparisons:

RAID1 (PCI)

write: 38.9 MB/s
read: 64.8 MB/s

Single Disk (PCI)

write: 59.4 MB/s
read: 71.9 MB/s

Categories: file systems, server

Remove Stale LVM Devices

January 23rd, 2010 No comments

Have an LVM device left on your system from a drive that was removed before pvremove was run?

1
$ sudo dmsetup remove /dev/mapper/removed-device
Categories: file systems, LVM