[Nottingham] lvm on raid & hdparm -tT looks pathetic!

[Martin]

Back in the land of hdd rather than mythical DD flash kaboom... ;-)


On a certain experimental system of mine with two sata1 hdds, using
hdparm -tT to get some read speeds I get:

1 GByte/s memory (cache) read in all cases;

18 MByte/s single partition (/dev/sda1 or /dev/sdb1);

80 MByte/s raid (/dev/md0);

18 MByte/s LVM (/dev/lvm-whatever...);


Whereby I've set up the LVM on top of a software mirror raid across the
sata1 hdds.


So why is the LVM performance so slow?

Or is this a measurement problem?


Any ideas?

Cheers,
Martin

-- 
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Martin Lomas
martin at ml1.co.uk
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