[mythtv-users] SATA Drive Failure

Kelly navykel at gmail.com
Sat Jun 25 18:17:12 UTC 2005


On 6/25/05, Allan Stirling <Dibblahmythml0015 at pendor.org> wrote:
> Kelly wrote:
> > Think I've found a source of my constant crashing. I have a Maxtor
> > SATA 250GB drive. I started poking around google and came up with the
> > hdparm test. I ran it and got
> >
> > Timing cached reads:   816 MB in  2.01 seconds
> >
> > A respectable IDE drive and do 3000mb in 2.00 seconds.
> >
> > So my drive is running at 20% efficiency. That will make a difference.
> >
> Ummm... No. You're reading the results wrongly, I'm afraid :)
> I would seriously doubt you'd see 1.5Gb / sec outside the datacentre.
> 150Mb / sec... _maybe_.
> 
> Cached reads are just that - It reads the same sector over and over.
> This means it's already in drive's read cache. So what you're seeing
> here is the transfer rate from the controller without (much) SATA
> latency, no seek latency, no rotational latency. That's not the test you
> want. You want 'buffered disk reads'. This is the (almost real) raw
> performance of the drive.
> 
> Here's the results from my array, which is a 8 disk RAID5, spread over 2
> SATA controllers on a PCI-X dual Xeon (yes, I believe overkill _is_ just
> a word):
> 
> hdparm -Tt /dev/sda
> 
> /dev/sda:
>  Timing cached reads:   2204 MB in  2.00 seconds = 1101.07 MB/sec
>  Timing buffered disk reads:  374 MB in  3.01 seconds = 124.31 MB/sec
> 
> The 'buffered disk reads' is the line you're looking for. And 124Mb /
> sec is quite good for this type of setup.
> 
> Cheers,
> 
> Allan.


My output
hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   968 MB in  2.00 seconds = 483.83 MB/sec
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate
ioctl for device
 Timing buffered disk reads:  152 MB in  3.05 seconds =  49.81 MB/sec
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate
ioctl for device


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