Re: 1x 3ware controllers vs. 2x 3ware controllers

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quoted

With the performance issues I'm seeing with the 8506-4LP's I have, I 

wouldn't 

quoted

recommend them to anyone currently...

The thread on LKML from a few days ago about mke2fs -j and 8506-4LP says it 
all, but basically and reasonable amount of I/O brings a Dual Opteron 

system 

quoted

to its knees.
And by reasonable I mean copying ISO images from a usb2 drive to a raid 5 

(4 x 

quoted

250GB maxtor) or even just formatting a 600MB partition.

I've been able to get nearly 1.5 Gbits/sec off of an 8506-8, with 8
250GB disks...  of course those are all 1 megabyte reads (but from
random locations).  Is your problem related to # of IO's, or size of
transfer?

# hdparm -tT /dev/sda

/dev/sda:
 Timing buffer-cache reads:   2232 MB in  2.00 seconds = 1115.61 MB/sec
 Timing buffered disk reads:  190 MB in  3.03 seconds =  62.76 MB/sec

bonnie++ concurs with this and gives us about 22MB/sec write performance.

Basically anything involving I/O is causing the system to crawl.
I can reliably reproduce this by doing:

	mke2fs -j /dev/sda7

Where sda7 is a 600GB partition.

Basically the system load goes orbital and responsivness goes out the window.
gkrellm only shows ~1MB/sec of disk activity and the processors (Dual Opteron) 
are twiddling their thumbs (top shows 100% 'wa' state for both processors), 
yet I can hardly do anything with any open applications.

Kernel is a 2.6.8rc1 kernel.org job.

- -- 
Mark Watts
Senior Systems Engineer
QinetiQ Trusted Information Management
Trusted Solutions and Services group
GPG Public Key ID: 455420ED

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