Re: Disk partitioning strategy?

[bruce@pixar.com (Bruce Perens)]

> ...and while we're on the subject, has anyone seen reports of how
> big an advantage you get from putting your swap partition on a
> separate drive from the rest of your system?

Memory is getting cheap (one sale here recently hit $12.50/MB). It pays to
get more RAM rather than disk if you worry about swapping.

I am currently running my swap and filesystem on separate drives. Indeed, they
are separate channels of the dual Triton DMA IDE controller on my motherboard.
In theory, it should help. In practice, I don't have much evidence, mostly
because I'm too busy with other Debian tasks to measure this.

If you buy a drive, put it on a DMA controller such as a bus-master SCSI or
the Triton chipset DMA IDE controller, so that the CPU is not burdened with
disk transfers. On my system the Triton runs 6-7 MBPS
from the fastest disk, while the SCSI (aic-7850 on motherboard) actually
runs slower at 5-6 MBPS. On most systems, the SCSI will be much faster than
the IDE.

There is also a big difference in drive speed. Note these numbers from
"hdparm -t". Both are for IDE drives in DMA mode on identical controllers.

Model=QUANTUM FIREBALL1280A
Timing buffer-cache reads:   32 MB in  1.27 seconds =25.20 MB/sec
Timing buffered disk reads:  16 MB in  2.65 seconds = 6.04 MB/sec
Estimating raw driver speed: 16 MB in  2.01 seconds = 7.94 MB/sec

Model=Conner Peripherals 340MB - CP30344
Timing buffer-cache reads:   32 MB in  1.27 seconds =25.20 MB/sec
Timing buffered disk reads:  16 MB in  8.09 seconds = 1.98 MB/sec
Estimating raw driver speed: 16 MB in  7.46 seconds = 2.15 MB/sec

I see that disk manufacturers are starting to quote rotational speed.

	Bruce
--
Pixar Animation Studios: Reality is not our business.
Pixar's "Toy Story" $184,849,036 domestic, $117.5M overseas and counting.
That makes it number 21 in box office figures of all films ever released.