[Ltsp-discuss] Re: [K12OSN] new server serial ATA or SCSI

Sudev Barar sudev at mantraonline.com
Sat Mar 20 01:02:10 UTC 2004


On Thu, 2004-02-26 at 08:18, Sudev Barar wrote: 
> I could not make out why variation in timing for /dev/mdo and /dev/md1
> made across the same two scsi drives in second server. Nor could I make
> out the difference in timings returned from IDE drives on third server
> as both are of the same specs.
[SNIP]
> Server three: Two IDE drives in raid0 array
> /dev/md0:
>  Timing buffer-cache reads:   128 MB in  0.54 seconds =237.04 MB/sec
>  Timing buffered disk reads:  64 MB in  1.65 seconds = 38.79 MB/sec
>  
> /dev/md1:
>  Timing buffer-cache reads:   128 MB in  0.53 seconds =241.51 MB/sec
>  Timing buffered disk reads:  64 MB in  1.63 seconds = 39.26 MB/sec
> 
> /dev/hda:
>  Timing buffer-cache reads:   128 MB in  0.56 seconds =228.57 MB/sec
>  Timing buffered disk reads:  64 MB in  1.23 seconds = 52.03 MB/sec
>  
> /dev/hdc:
>  Timing buffer-cache reads:   128 MB in  0.58 seconds =220.69 MB/sec
>  Timing buffered disk reads:  64 MB in  2.26 seconds = 28.32 MB/sec

Catching up on my own post and questions. For any one who is interested
it turned out that the IDE cable in the third server was faulty and the
drive was giving slower speeds. AFter the change the following results
are now given:
/dev/hda:
Timing buffer-cache reads:   128 MB in  0.55 seconds =232.73 MB/sec
Timing buffered disk reads:  64 MB in  1.23 seconds = 52.03 MB/sec

/dev/hdc:
Timing buffer-cache reads:   128 MB in  0.55 seconds =232.73 MB/sec
Timing buffered disk reads:  64 MB in  1.42 seconds = 45.07 MB/sec

/dev/md0:
Timing buffer-cache reads:   128 MB in  0.56 seconds =228.57 MB/sec
Timing buffered disk reads:  64 MB in  1.04 seconds = 61.54 MB/sec

/dev/md1:
Timing buffer-cache reads:   128 MB in  0.56 seconds =228.57 MB/sec
Timing buffered disk reads:  64 MB in  1.04 seconds = 61.54 MB/sec

Improvement from 38 to 60 MB/sec !!!
So apart from debate about SATA / SCSI the hardware issues also [play
important role. This was a major learning for me.
-- 
Sudev Barar

Learning Linux






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