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Re: disk diagnostics

From: "Freddie Cash" <fcash-ml@xxxxxxxxxx>
Date: Tue, 25 Jul 2006 13:29:53 -0700 (PDT)

On Tue, July 25, 2006 12:34 pm, Bill Hacker wrote:
> Pieter Dumon wrote:
>> how can I diagnose my disk read/write throughput under DFLy ? my
>> system runs well except that untarring even small tar files or
>> deleting files takes a lot of time (e.g. the removal of
>> /usr/obj/usr/src/world_i386 during a make buildworld takes about 25
>>  minutes (I admit it's got a lot of files, but still....)).
>> I don't know if it can have anything to do with my strange
>> configuration of having the two harddisks on ATA1 while the CDs are
>> on ATA0. The disk with the DFly slice is only UDMA33 (there are no
>> DFLy
>> slices on the other disk), but still, under windows and linux I
>> don't have this slow disk access.
>> ad2: 28629MB <ST330621A> [58168/16/63] at ata1-master UDMA33
>> ad3: 76319MB <WDC WD800BB-00JHC0> [155061/16/63] at ata1-slave
>> UDMA100
>> acd0: DVD-R <AOPEN DUW1608/ARR> at ata0-master PIO4
>> acd1: CDROM <CD-ROM 36X/AKU> at ata0-slave PIO4

> Agree that is not an optimal set up - faster IDE drives uusally fare
> best on 80-pin cable to ad0 (master) and ad2 (master) with CD's as
> slaves, or better yet, on a PCI-bus add-on controller so there is no
> master/slave speed difference.

It really depends on what your data transfers across the IDE bus will
look like.  You want to put the sender and receiver on separate
channels (not as master/slave on the same channel), regardless of what
the devices are.

So, if you do mostly CD->HD or HD->CD transfers (ripping or burning
CDs/DVDs) then you will want the HD and CD to be master on separate

If you do mostly HD->HD transfers, you will want those as master on
separate IDE channels.

If you do mostly CD->CD transfers (on-the-fly copying of CDs/DVDs),
then you will want them on separate channels (preferably as master,
but that's not always possible with only onboard IDE controllers

If you do a fairly balanced mix of HD->HD and HD->CD, then it doesn't
really matter where the devices are.

And you'll want your fastest device to be master on the IDE channel,
if you have multiple devices per channel.

Granted, the best setup is to only have a single device on each IDE
channel.  And to have add-on IDE controller sitting on separate PCI
buses from other devices (if possible).

Freddie Cash, LPCI-1 CCNT CCLP        Helpdesk / Network Support Tech.
School District 73                    (250) 377-HELP [377-4357]

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