From: Terrence Martin <tmartin@physics.ucsd.edu>
To: linux-scsi@vger.kernel.org
Subject: Write Performance double Read Performance
Date: Mon, 22 Mar 2004 11:32:06 -0800 [thread overview]
Message-ID: <405F3F36.6020109@physics.ucsd.edu> (raw)
I have the following system(s)
Dual 2.8 Ghz Xeon 2U Supermicro Server with 2GB RAM
Qlogic QLA2310f Controller
attached to an...
Infortrend A16F with 16 300GB WD IDE PATA Drives
The array as a RAID 5 Array with 3 partitions of 1.4TB each. I have
mounted one of the partitions to test.
The OS is....
Fedora Core 1 with the latest Fedora 2.4 Kernel (2.4.22-1.2174.nptlsmp)
I have compiled the QLA drivers from the Qlogic site and am using v6.06.10.
The problem I am noticing is that while doing an IOZone performance test
I get nice write performance when the test gets to large files. However
my read performance seems to be a little over half my write. I thought
the read should always be faster than the write?
Command line used: /opt/iozone/bin/iozone -Ra -g 4G -i 0 -i 1
Eg. Copy paste from IOZone run
KB reclen write rewrite read reread
2097152 64 154313 171266 91012 92388
2097152 128 154125 170701 89532 82991
2097152 256 151473 169734 86227 85231
2097152 512 150925 168767 84953 86313
2097152 1024 154947 175371 84576 85733
2097152 2048 154581 175161 84865 85233
2097152 4096 155754 175689 85229 86450
2097152 8192 155847 175645 85320 86052
2097152 16384 155500 175313 84817 86864
I only notice this performance drop once I get into large reads. Here
when the file is half RAM performance is very good.
KB reclen write rewrite read reread
1048576 64 174326 236646 1571371 1722042
1048576 128 171660 236849 1552772 1699937
1048576 256 173722 239855 893958 938153
1048576 512 171075 238875 660975 683853
1048576 1024 169105 239178 651627 675901
1048576 2048 167846 240387 649875 673732
1048576 4096 168663 238126 653533 675654
1048576 8192 171406 239028 646698 669387
1048576 16384 171545 237270 647777 669695
Before I went down the road of compiling various kernels etc I thought I
would post this to linux-scsi to see if it is just some configuration
setting to a driver or kernel parameter that needs to be tweaked. Of
course I could be completely reading this wrong but bonnie++ also
appears to give similar results and vmstat is similarly low on the read
side.
Thanks,
Terrence
next reply other threads:[~2004-03-22 19:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-22 19:32 Terrence Martin [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-03-23 11:28 Write Performance double Read Performance James Pearson
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