[ale] A faster Java box - any tips ??

[Greg Freemyer]

On 10/19/05, Greg <runman at speedfactory.net> wrote:
> Good question.  I am thinking that I cannot take advantage of any parallel
> processing - that my IDE can only do it in serial manner, else my dual
> Opteron should be smoking the laptop (3.6 GHZ / 2 GB of RAM).  However it is
> another avenue that I haven't thought about but I can look into it.
>
> Thanks for the tip !
>
> Greg

I haven't really been following this thread, but you have a dual
opteron without any form of RAID?

Even if you don't care about reliability you NEED raid just for the
speed it provides.  As I recall, all forms of raid (0,1,5,6,10) are
faster than a simple disk.  Also IDE is notoriously slow, so you need
to evaluate ways to accelerate it.

I'm sure on some compute intensive jobs a simple disk is not the
bottleneck, but on most jobs disk i/o is the bottleneck.  Adding a cpu
does nothing to fix the problem.  In fact it can make it worse by
trying to do more work around the disk thus causing lots of very slow
disk seeks.

One easy way to tell is to use top.  If you have idle and/or wait time
during your java compiles then you are waiting on the disk subsystem.

Assuming your disk subsystem is the bottleneck.........

Going to raid 0 (or 1) with 2 IDE drives set as master may help.  (I
never tried it, but IDE has issues with the lack of connect/disconnect
logic on the bus so I don't know if you can utilize 2 at once or not. 
ie. With a Master / Slave setup only one device at a time can be
utilizing the bus and that includes seek time, so for the multiple
millisecs a seek takes, the other device is not allowed to use the IDE
bus.  Not sure what happens if you have 2 IDE buses and 2 masters.)

For max. performance in a disk subsystem you really need to move a way
from standard IDE.

I personally use the 3ware IDE Hardware RAID 0 controllers ($100 -
$150 for a 2-port card).  Uses the same low-cost drives, but the
controller pretends to be a SCSI controller so the Linux kernel can
send the controller a seek command, then go back to compiling or
whatever.  This eliminates

Using 2 (or more) SCSI drives in a RAID 0 setup should be even better,
but also more expensive.

One other possiblity I don't know about is using SATA drives in a RAID
0.  I don't know if those can be seeking simultaneously or not.

Greg
--
Greg Freemyer
The Norcross Group
Forensics for the 21st Century