[leglug-users] Harddisk performance

[Alaa Salman]

Yes, i am aware of sdparm. And if i remember correctly, hdparm is not to 
be trusted when used on SATA disks. But in every thread that i read 
regarding sdparm, i see people measuring output on SATA disks using hdparm.

Plus sdparm does not seem to work correctly. At least for me. For 
example check out this output.

john at Cenarius:~/ISOs$ sudo sdparm -v -a /dev/sda
     /dev/sda: ATA       WDC WD2500JD-98H  08.0
     Request Sense cmd: 03 00 00 00 40 00
request sense:  Fixed format, current;  Sense key: Illegal Request
  Additional sense: Invalid command operation code
REQUEST SENSE failed

I didn't investigate this a lot, but i know that the -a option will give 
you all the attributes by querying the disk. So this should work if 
you're not tweaking anything.

If this performance seems weak. Then i would reserve some time to 
investigate further.

By the way, the numbers that i got, are from an idle state. So my 
computer wasn't running vmware at the time, just some regular 
applications such as browser and gaim. However, since vmware uses a lot 
of swapping(if you don't tweak it), that is when i notice the slow side 
of the operations.

Also, i am not sure about my HDs specs. I should probably check what's 
on the labeling(never occurred to me, since i trust hdparm more than i 
trust the theoretical limits that manufs. put on there), but it is about 
2-3 years old.

Alaa

Edmond Abrahamian wrote:
> On Mon, March 19, 2007 2:02 am, fire said:
> 
>> I believe there's a new util called sdparm for managing SCSI-like
>> devices under Linux, I haven't fiddled around with that, yet! :P
>>
>> Hope this helps, but anyhow, 50MB/sec on SATA is ok, here are my stats
>> on a P4 3.2GHz with 2GB of RAM and 80GB HDD running VMware workstation
>> with 2 VMs.
>>
>> /dev/sda:
>>  Timing cached reads:   4168 MB in  2.00 seconds = 2084.12 MB/sec
>>  Timing buffered disk reads:  176 MB in  3.03 seconds =  58.12 MB/sec
> 
> 
> hmmm. my sata drive is rated at 300mb/sec (buffered). I wouldn't be
> too happy if I get 50 on a buffered read. typically, earlier sata
> drives are rated at 100mb/sec buffered so 50 is still off.
> 
> Of course you have to be able to believe the output of hdparm(8). I've
> heard that hdparm does not work very well with sata at this time, but
> then I can't remember where I read this so I can't substantiate my
> claim.
> 
> Regards,
> 
>   -- Edmond
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