[mythtvnz] partitions

[Hadley Rich]

On Thu, 2009-05-14 at 20:26 +1200, Sam Hadley-Jones wrote:
> That said, I think its safe to assume that the RAID 5 array is a serious
> bottleneck. Theoretical speed of the array should be close to 240MB/s. I'm
> thinking its either the RAID 5 parity computation or serious latency issues
> between the motherboard controller and the PCIe controller.

For comparison, here's a RAID5 (no LVM) array on my home server;

hads at beaver:~$ sudo hdparm -t /dev/sdb

/dev/sdb:
 Timing buffered disk reads:  194 MB in  3.02 seconds =  64.14 MB/sec
hads at beaver:~$ sudo hdparm -t /dev/sdc

/dev/sdc:
 Timing buffered disk reads:  310 MB in  3.01 seconds = 102.82 MB/sec
hads at beaver:~$ sudo hdparm -t /dev/sdd

/dev/sdd:
 Timing buffered disk reads:  296 MB in  3.02 seconds =  98.09 MB/sec
hads at beaver:~$ sudo hdparm -t /dev/sde

/dev/sde:
 Timing buffered disk reads:  222 MB in  3.03 seconds =  73.38 MB/sec
hads at beaver:~$ sudo hdparm -t /dev/md0

/dev/md0:
 Timing buffered disk reads:  380 MB in  3.00 seconds = 126.47 MB/sec
hads at beaver:~$ 


You'll see that sdb and sde are slow, they are on an old PCI SATA
controller, the others are on the onboard controller from a cheap ASUS
motherboard.

hads

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