[mythtv-users] RAID5 ATA IDE hardware card
recommendations formythbackend machine
Dave.Howorth at acm.org
Sat Dec 11 00:26:19 UTC 2004
Yan-Fa Li wrote:
>>> Think of an old fashioned 78RPM record player. The disc spins at
>>> a constant speed, 78RPM. The outer part of the disc is moving
>>> faster than the inner part, but the time the head has to read and
>>> write is the same regardless of where you are on the disc.
>>> Therefore the inner part gets data faster because it has to spin
>>> much less to read the same amount of data assuming all the tracks
>>> hold exactly the same amount.
As John Andersen said, this is no longer true. The tracks *don't* hold
the same amount and it's the outer part of the disk that gets data faster.
That page appears to describe how disks worked some years ago.
Try this one for a different explanation that I believe describes
'Zoned recording' is the important difference.
> /dev/md1: Timing buffered disk reads: 136 MB in 3.01 seconds =
> 45.18 MB/sec
The figures above are for the outside of the disk, those below for the
> /dev/md4: Timing buffered disk reads: 98 MB in 3.01 seconds =
> 32.56 MB/sec
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