[mythtv-users] Disk I/O problems?

Larry Finger Larry.Finger at lwfinger.net
Fri Aug 22 17:42:07 UTC 2014


On 08/22/2014 11:46 AM, Lindsay Mathieson wrote:
> Since upgrading to 0.27.3 I've been having bad problems with playback stutter 
> and failures.
> 
> 
> hdparm on my disks seem somewhat slow:
> 
> sudo hdparm -tT /dev/sda
> 
> /dev/sda:
>  Timing cached reads:   2134 MB in  2.00 seconds = 1067.96 MB/sec
>  Timing buffered disk reads: 232 MB in  3.01 seconds =  77.01 MB/sec
> 
> Is this normal for WD 1TB Greens? unfortunately I don't know what they were in 
> the past :)

For my three 1TB disks, I get

finger at desktop:~> sudo hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   1942 MB in  2.00 seconds = 971.63 MB/sec
 Timing buffered disk reads: 500 MB in  3.00 seconds = 166.62 MB/sec
finger at desktop:~> sudo hdparm -tT /dev/sdb

/dev/sdb:
 Timing cached reads:   1962 MB in  2.00 seconds = 980.90 MB/sec
 Timing buffered disk reads: 260 MB in  3.01 seconds =  86.52 MB/sec
finger at desktop:~> sudo hdparm -tT /dev/sdc

/dev/sdc:
 Timing cached reads:   1972 MB in  2.00 seconds = 986.71 MB/sec
 Timing buffered disk reads: 458 MB in  3.01 seconds = 152.33 MB/sec

My drives are

/dev/sda:
Model Family:     Seagate Barracuda 7200.14 (AF)
Device Model:     ST1000DM003-1CH162

/dev/sdb:
Model Family:     Western Digital Caviar Green
Device Model:     WDC WD10EADS-00L5B1

/dev/sdc:
Model Family:     Seagate Barracuda 7200.14 (AF)
Device Model:     ST1000DM003-9YN162

The buffered reads from the Seagates are nearly twice as fast as the WD. As far
as I know, my system is OK.

Larry



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