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--></style></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt'>I wanted to ask, what is the best practice when it comes to building the OST. We have Block volumes we can provision and each of them can deliver 480 MB/s throughput and they can be attached to multiple compute nodes in sharable read/write mode. I have a 25Gbps (3125 MB/s) network between OSS and Storage devices (aka: block volumes). Lustre clients nodes also have 25Gbps network connection to OSS nodes. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Options: <o:p></o:p></span></p><ol style='margin-top:0in' start=1 type=1><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'><span style='font-size:11.0pt'>On OSS servers, I setup 7 or more OST’s (7*480=3360MB/s) and set Stripe Count to 7 or more, to ensure clients get max throughput performance possible. <o:p></o:p></span></li><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'><span style='font-size:11.0pt'>On OSS servers, I setup a Linux software RAID0 of 7 block volumes, set Stripe count = 1 , to ensure clients get max throughput performance possible. I can setup multiple OSTs for the OSS, with each OST been a RAID0 of 7 block volumes. <o:p></o:p></span></li></ol><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-size:11.0pt'>Question</span></b><span style='font-size:11.0pt'>: Is it better to use Option2 or let clients use stripe count 7 or more, to get the max performance from the file system. Most clients will use 1 File per process when writing files to file system. With Option2, I am trying to hide the Storage backend throughput complexity from clients. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Our Block volumes are already replicated, so I don’t need to do RAID1, RAID5 or RAID6 at the Linux s/w RAID level. In option2, I am using RAID0, so I can get throughput from 7 Block volumes which matches the network speed I will have between most of my Lustre clients and Lustre OSS servers. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Another question is, has anyone implemented HA across 2 OSS nodes pair/building block and using OST’s which are linux software RAID0. Issue I am facing is after I create RAID0 on OSS1, I have to reboot OSS2 to make it visible on OSS2. Then if I reboot OSS1, the RAID0 (/dev/md127) is gone on OSS1. Wondering if this is technically even feasible to have HA with Linux software RAID0 ?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'> <img width=519 height=282 style='width:5.4062in;height:2.9375in' id="Picture_x0020_1" src="cid:image001.png@01D5C613.5A531410" alt="A screenshot of a cell phone
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