Re: [gentoo-user] Normal disk speed?

[Florian Philipp <lists@f_philipp.fastmail.net>]

Am Donnerstag 30 September 2010, 12:58:36 schrieb Adam Carter:
> Taring my mp3 collection from 2.5in 500MB internal sata drive (sda) to
> esata 3.5in 500MB drive (sdb) and it seems slow. In vmstat i can see that
> the external drive writes faster than the internal can read (external has
> periods of inactivity)
[...]
> So 21221MB in 610 seconds = 35 MB/s
> 
> # hdparm -t /dev/sda
> 
> /dev/sda:
>  Timing buffered disk reads:  220 MB in  3.01 seconds =  73.14 MB/sec (77
> with --direct)
[...] 
> So the should i expect filesystem (reiser3) and other overhead to cut the
> read performance to less than half of what hdparm reports? Anything else i
> can look at to speed it up? Im using CFQ io scheduler.

35 MB/s is a pretty normal value for a 5400 RPM laptop HDD.

An HDD gets slower when you read the inner tracks.  The angular velocity is 
constant (5400 RPM) while the tangential velocity gets lower with the radius.

Inner tracks are mapped to the sectors at the far end of the partition table. 
That's why you should always put swap and system partitions at the front of 
your partition table and use its end for bulk data.

I guess your mp3 collection is stored somewhere at the middle or end of your 
internal disk (inner tracks) while your external disk is nearly empty and 
therefore stores data on the outer tracks. 

Hope this helps.
Florian Philipp