Something

h36sa@gameinwatch ~ $ sudo hdparm -Tt /dev/md5

/dev/md5:
 Timing cached reads:   940 MB in  2.00 seconds = 469.69 MB/sec
 Timing buffered disk reads:  272 MB in  3.02 seconds =  90.13 MB/sec
h36sa@gameinwatch ~ $ sudo hdparm -Tt /dev/md4

/dev/md4:
 Timing cached reads:   940 MB in  2.00 seconds = 469.50 MB/sec
 Timing buffered disk reads:  166 MB in  3.00 seconds =  55.28 MB/sec
h36sa@gameinwatch ~ $ sudo hdparm -Tt /dev/vg/home

/dev/vg/home:
 Timing cached reads:   938 MB in  2.00 seconds = 468.79 MB/sec
 Timing buffered disk reads:  168 MB in  3.02 seconds =  55.60 MB/sec

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/dev/md5 is 2x120gb raid0
/dev/md4 is 2x80gb raid0 (one disk is 5400rpm)
/dev/vg/home is an lvm with both /dev/md5 and /dev/md4 physical volumes