[Xen-users] Disk IO

To:	Xen Users <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject:	[Xen-users] Disk IO
From:	Paras pradhan <pradhanparas@xxxxxxxxx>
Date:	Mon, 25 Jan 2010 14:45:27 -0600
Delivery-date:	Mon, 25 Jan 2010 12:46:13 -0800
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Hi,

I am doing disk IO test in dom0 and domU

dom0 has 1 CPU with 4GB of RAM and hardware raid 1

domU has 1 CPU with 1 GB of RAM. domU image is a filebacked image file in CLVM/GFS2 partition which connected to storage via 4mbps Fibre SAN.

I am using iozone to test the performance and here are the outputs

dom0:

"Record size = 4 Kbytes "

"Output is in Kbytes/sec"

" Initial write " 282829.86

" Rewrite " 469707.22

" Read " 657510.62

" Re-read " 1293660.70

" Reverse Read " 837261.74

" Stride read " 861772.51

" Random read " 574933.67

" Mixed workload " 486711.21

" Random write " 395390.98

domU:

"Record size = 4 Kbytes "

"Output is in Kbytes/sec"

" Initial write " 133933.96

" Rewrite " 394235.88

" Read " 710423.94

" Re-read " 508824.84

" Reverse Read " 407579.28

" Stride read " 401205.93

" Random read " 410340.80

" Mixed workload " 338249.12

" Random write " 309791.69

command used: /opt/iozone3_327/src/current/iozone -R -l 5 -u 5 -r 4k -s 100m -F /home/f1 /home/f2 /home/f3 /home/f4 /home/f5 | tee -a /tmp/ioz

one_results.txt &

As we can see above in domU, the drop is almost 50% (referring write and re write). Is this normal? Can it be tuned?.

Also any recommended tool to check IO ?

Thanks!

Paras.

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