[mythtv-users] SATA and DMA (SIIG 3112)
Brian Wood
beww at beww.org
Fri Mar 31 22:49:06 UTC 2006
On Mar 31, 2006, at 2:26 PM, leland sindt wrote:
> What does "hdparm -tT" show you?
>
> hdparm -tT /dev/sda
>
> /dev/sda:
> Timing cached reads: 2256 MB in 2.00 seconds = 1127.93 MB/sec
> Timing buffered disk reads: 112 MB in 3.08 seconds = 36.41 MB/sec
>
>
> Two SD and one HD stream is a *lot* of data, you may be hitting
> the real limit of the drive system.
>
> Yes, it is a lot of data... My orig plan was to use a SATA II
> controller
> (but didn't know at the it required pci-e at the time)
There is no (n)ATA drive available on the market at this time that
can even keep up with a SATA-150 interface. The so-called SATA-II
(not really a standard yet) may be interesting in the future but
right now it belongs to the marketing people and not the engineers.
>
> Hmmm... Anybody got numbers/experience with Hardware/Software Raid
> 0? Did it result in increased bandwidth?
> (Less likely with software, I know)
I record on a RAID-0 software array with 2 SATA drives:
/dev/hda:
Timing cached reads: 2608 MB in 2.00 seconds = 1303.92 MB/sec
Timing buffered disk reads: 184 MB in 3.00 seconds = 61.33 MB/sec
/dev/md0:
Timing cached reads: 2648 MB in 2.00 seconds = 1323.92 MB/sec
Timing buffered disk reads: 338 MB in 3.03 seconds = 111.62 MB/sec
Which is more or less what you'd expect, given a little overhead for
the software RAID.
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