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</o:shapelayout></xml><![endif]--></head><body lang=FR link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Hi Jan !<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>This is a tough question. It depends on many parameters, starting with the size of the requested IOs. There are a couple of good articles on the net talking about that, including these :<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US style='color:#1F497D'><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='color:#1F497D'>2 from Scott LOWE, wich are fairly clear and interesting from the IOPS estimation methodology standpoint :<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><a href="http://www.techrepublic.com/blog/datacenter/calculate-iops-in-a-storage-array/2182">http://www.techrepublic.com/blog/datacenter/calculate-iops-in-a-storage-array/2182</a><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><a href="http://www.techrepublic.com/blog/datacenter/storage-array-capacity-performance-vs-cost/2239">http://www.techrepublic.com/blog/datacenter/storage-array-capacity-performance-vs-cost/2239</a><o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US style='color:#1F497D'><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='color:#1F497D'>This one from HP gives some interesting numeric values about the drives they supply in their servers :<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><a href="http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1305886571915+28353475&threadId=1122630">http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1305886571915+28353475&threadId=1122630</a><o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US style='color:#1F497D'><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='color:#1F497D'>There’s also this one from Duncan EPPING, that provides a few additionnal informations :<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><a href="http://www.yellow-bricks.com/2009/12/23/iops/">http://www.yellow-bricks.com/2009/12/23/iops/</a><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>But unfortunately, the real and immediate answer to your question is “It depends”! </span><span lang=EN-US style='font-family:Wingdings;color:#1F497D'>J</span><span lang=EN-US style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Hope this helps,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Best regards,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Pascal.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>De :</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> drbd-user-bounces@lists.linbit.com [mailto:drbd-user-bounces@lists.linbit.com] <b>De la part de</b> Jan.Dreyer@bertelsmann.de<br><b>Envoyé :</b> vendredi 20 mai 2011 10:11<br><b>À :</b> drbd-user@lists.linbit.com<br><b>Objet :</b> [DRBD-user] Performance question<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-US>Hi,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>I have a question that is not directly related to drbd, but more to performance of drbd on HW-Raid.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>This is our configuration:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>2 HP machines with ubuntu-Linux (LTS)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>configured HW Raid5 on 4 disks (DG146BB976 = 146.8GB 10k SAS) on each of the two machines<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>LVM on that HW-RAID with 3 logical volumes (system, swap, data)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>DRBD on data-volume (ext4) over dedicated GiB-interface<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Now the question: what performance (iops) can I expect from that configuration? I don’t really found useful information in the net, so I ask here. The drbd-interface gives about 40 tps (iostat -dk drbd1 5), which seems low to me. Also suspicious: %util is many times more than 98, and await is nearly always greater than svctm. These hints would allow to suspect an error, if I had only one disk – I have no idea which values to expect on my Raid5-configuration.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>Has anyone a hint or a guidance to how to calculate expectable values?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:36.0pt'><span lang=EN-GB>Greetings<o:p></o:p></span></p><p class=MsoNormal style='margin-left:36.0pt'><span lang=EN-GB>Jan Dreyer<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>