Re: Partitioning for Speed
hi ya
On Mon, 31 Mar 2003, Jeff wrote:
> I've seen a reference to two regarding the location of a partition on
> the HDD being faster than other parts of the HDD. I've been trying to
> get a definitive answer on this and it's still not clear to me.
the disk spins at the same rotational rpm ... its the "same" speed
what you can do, is to add more data ( sectors ) on a given tract
say 64 sectors per track vs 256 sectors on the outer tracks
( doing so screws up your pll and other analog signals
( but is worth it if you want to maximize capacity
- whether reading 64* 512bytes/sector or 256 * 512byte/sector
is better/worst is up to the app ... and how data is written
- less moving of the heads is generally faster as it takes too long
to move the head relative to just reading data
- track 0 ( first partitions ) is ALWAYS on the outside of the disk
- example pic of partition layout on the disk
http://www.linux-1u.net/Partition/
- careful selection of bytes per sector also helps
512 byte /sector vso 1024 or 2048 bytes/sector
( bytes per inode )
- but all that is lots-o-headaches
and you'd need to write data to disk to take those extra
tweeks into account for maximum benefit
- calculate ... 5400rpm vs 7200rpm vs 10,000rpm vs 15,000rpm
- defaults is 512 bytes/sector
- defaults is 64 sectors per track
- defaults is "n" number of physical heads ( number of platters )
- for each revolution of disk ... you get xxxKB/sec of disk
transfer
- ignore all those marketing numbers of ata-66, ata-100, ata-133
- for ide disks -- 1st round no-brainer speed comparason/optimization
- fiddle with some of the hdparm options and check its effects
- hdparm -tT /dev/hda
- hdparm -d 1 -u 1 -m 16 -c 3 /dev/hda
( make sure your disk supports the options first )
- turn on dma ( -d 1 )
- turn on intr ( -u 1 )
- turn on multicount ( -m 16 )
- turn on 32bit io ( -c 3 )
- set the proper ATA speed ( -X69 for ata-100 )
http://www.linux-1u.net/Disks/hdparm.txt
- dont forget to account for 2MB disk cache and 8MB disk cache
- simpler to just add a 2nd spindle ( /dev/hdc ) and be able
to read data 2x faster than with one disk ( /dev/hda )
- initial writing of data and parity will be slightly slower
- anybody ever wonder what the differences are between the following:
http://www.linux-1u.net/Memory/#DDR
100Mhz pci-100
133Mhz pci-133 sdram
DDR memory ... ( 2x FSB )
200-FSB PC-1600
266-FSB PC-2100
333-FSB PC-2700
400-FSB PC-3200 memory you need, maximize cpu performance
533-FSB PC-4300 ??? ( no such thing )
and than try to find 256MB/512MB/1G registered ECC memory for the
cpu you're using
- they only make PC-2100 registered ecc memory ... thats
reasonably priced
- other ways to improve your system
http://www.linux-1u.net/Tuning/
- fun stuff
c ya
alvin
> 1. What part of the HDD is faster, the inside (closest to the center
> of the platter) or the outside?
>
> It makes some sense to me that the outside would be faster due the
> fact that it's moving faster, but this may not be a determining
> factor.
>
> 2. When using cfdisk to partition, does it start the first partition
> by default at the beginning, or on the inside, of the HDD?
>
> IIRC, it refers to this as "the beginning of the free space".
>
> 3. I would want to put my swap and / partitions in the fastest part
> of the HDD, leaving /home and /usr/local for the rest of the
> drive. Does this make sense? [That's how I like to partition,
> those four mount points.]
>
> My intention here is to learn about the HDD and partitioning for
> speed in general. My purpose is general usage, nothing specific.
>
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