[mythtv-users] OT? Hardware Differences

R. G. Newbury newbury at mandamus.org
Thu Apr 13 17:25:29 UTC 2006


Brian Wood wrote:
> On Apr 13, 1989, at 8:25 AM, R. G. Newbury wrote:
> 
> 
>>This is a little offthread but it does affect my use of myth. And this
>>list has shown that it is a source of deep knownledge about linux.
>>
>>I have 2 exactly similar 40G hard drives: model IC35L040AVVN07-0.  
>>Bought
>>the same day, same order.
>>
>>Playing with hdparm I can set the master /dev/hda to use udma=5 (using
>>the -X69 parameter.
>>The slave /dev/hdb will only do udma=2.
>>
>>As a result, although the cached read speeds are similar at about
>>730MB/s, the buffered read on hdb is 19.6MB.s versus 45 MB/s on hda
>>
>>The only difference I can see is that hdb reports:
>>
>>AdvancedPM=yes: unknown setting while hda reports AdvancedPM=yes:
>>disabled (255), and attempting to set APM on hdb gives the following
>>error:  HDIO_DRIVE_CMD failed: Input/output error
>>
>>It appears that neither APM nor acoustic management features actually
>>get changed/set when I use hdparm... Weird!
>>
>>I can get/set the other commands/switches on the drive so this is more
>>than a little weird.
>>
>>I want to move this drive to my mythbox and do the OS install onto it,
>>and use the entirety of the present 120G for recording...But the
>>throughput problem puts this plan in doubt. Any thoughts anyone.
> 
> Are you using an 80-conductor UDMA-type cable ?? You can get strange  
> results if you don't use one of these.
> 
> Have you tried swapping the drives and seeing if the "problem" drive  
> changes to the other one?

Both drives are on the same 80 conductor cable IIRC and the problem 
drive has no OS, so 'swapping' them would be difficult to implement, or 
are you suggesting that it may be the position on the cable which is the 
problem?

Geoff



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