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Re: Low read performance when using /dev/md* devices

debian@xxxxxxx wrote:
> I got very low read performance when I'm using /dev/md* devices (software
> RAID0). The write performance is twice the read performance.
> 
> My configuration is two USB 2.0 hard drives on separate USB 2.0 controller
> ports.
> 
> Case 1:
> 
> Using /dev/md* directly on the /dev/sda and /dev/sdb devices gives 20MB/sec
> with both read and write operations. However, when using:
> 
> Case 2:
> 
> # losetup -e aes256 /dev/loop1 /dev/md1
> # mount /dev/loop1 /mnt/hd
> 
> gives 18 MB/sec performance on write operations, but 10 MB/sec performance
> on read operations.

What kernel version are you using? 2.4 or 2.6?
If you are using 2.6 kernel, are you using anticipatory I/O scheduler?

Have you tried different values for lo_prealloc= and lo_nice= settings?
These are explained in section 9 of loop-AES' README file.

-- 
Jari Ruusu  1024R/3A220F51 5B 4B F9 BB D3 3F 52 E9  DB 1D EB E3 24 0E A9 DD

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