Disk Throughput

Disk Throughput

Post by amshai.. » Sun, 22 Oct 2000 09:39:19



How do I determine disk throughput, adapter throughput and stuff.

Actually I know by experience that for SSA you can reach a tpf of 150
while on SCSI you can reach a tps of 100. I want to validate it.
Now lets say that my adapter has some throughput how can I validate
that.

Arshad.

Sent via Deja.com http://www.deja.com/
Before you buy.

 
 
 

Disk Throughput

Post by Rodney Clar » Thu, 26 Oct 2000 04:00:00


get the program bonnie
Look for it on the net it lets you generate i/o in it's various forms.
Will probably help in the benchmarking exercise.

> How do I determine disk throughput, adapter throughput and stuff.

> Actually I know by experience that for SSA you can reach a tpf of 150
> while on SCSI you can reach a tps of 100. I want to validate it.
> Now lets say that my adapter has some throughput how can I validate
> that.

> Arshad.

> Sent via Deja.com http://www.deja.com/
> Before you buy.


 
 
 

Disk Throughput

Post by Walte » Fri, 27 Oct 2000 01:29:37


Arshad,

I don't know of any tool that will give you a single number, but if you
run iostat, it will give you a general idea of how utilised each disk
is. It is not as clean cut as you want it, but it is a start.

Hope this helps,
--
Walter Lolham  |  Sanderson Local Government Solutions
               |  13th Level, 33 Berry St, North Sydney, NSW, Australia
               |  Phone:  +61-2-9926-2800 (-2888 FAX)


> How do I determine disk throughput, adapter throughput and stuff.

> Actually I know by experience that for SSA you can reach a tpf of 150
> while on SCSI you can reach a tps of 100. I want to validate it.
> Now lets say that my adapter has some throughput how can I validate
> that.

> Arshad.

> Sent via Deja.com http://www.deja.com/
> Before you buy.

 
 
 

1. Interesting disk throughput performance problem

Hi.  I'm running into some disk throughput issues that I can't explain.
Hopefully someone reading this can offer an explanation.

One of my machines is running 2.4.5 and has 2 hard drives: a 7200 rpm
ATA100 Maxtor and a 5400 rpm ATA33 IBM.  Each drive is a master on its own
controller (AMI CMD649 as found on the IWill KT266-R).  Both drives contain
reiserfs 3.6x filesystems.  

By all local benchmarks, the 7200 rpm drive is the faster drive.  But this
doesn't seem to be the case for large files originating from remote clients.  
Witness:

My crude test involves scp'ing a 100MB file from another machine on my home
network over 100bT ethernet.

1)  scp to the 5400rpm drive:  roughly 10MB/sec.  
2)  scp to the 7200rpm drive:  roughly 2MB/sec.  

I've tried 'tail' and 'notail' mount options with no change (as expected since
this is a single large file).  I suspect that the machine would become CPU-bound
somewhere in the 20MB/sec range (see below for my reasoning).

I see the same sort of behavior using Samba though not nearly as
pronounced (the 5400rpm drive is merely 2x as fast as the 7200rpm drive).

Okay.  Since the test involved 2 separate drives with different geometries,
I figured this might be due to physical block location.  Perhaps the file
is getting allocated to the fastest cylinders on the 5400 rpm drive and
the slowest cylinders on the 7200 rpm drive.  Or it could be a fragmentation
issue.

So I tried the test locally:  with the file stored on the 5400rpm drive,
scp it to localhost and write it to the 7200rpm drive.  Results were a little
below 10MB/sec (CPU near 100% presumably due to encrypting/decrypting on
the fly).

Any ideas why the 7200rpm drive performs so poorly for remote clients but
performs wonderfully well when those same operations are performed locally?

Jimmie

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