The PERC 6 and H800 use megaraid_sas, I'm currently running 00.00.04.17-RH1.
The max_sectors numbers (320) are what is being set by default- I am able to set it to something smaller than 320, but not larger. Kevin On Wed, 11 May 2011, Kevin Van Maren wrote: > You didn't say, but I think they are LSI-based: are you using the mptsas > driver with the PERC cards? Which driver version? > > First, max_sectors_kb should normally be set to a power of 2 number, > like 256, over an odd size like 320. This number should also match the > native raid size of the device, to avoid read-modify-write cycles. (See > Bug 22886 on why not to make it > 1024 in general). > > See Bug 17086 for patches to increase the max_sectors_kb limitation for > the mptsas driver to 1MB, or the true hardware maximum, rather than a > driver limit; however, the hardware may still be limited to sizes < 1MB. > > Also, to clarify the sizes: the smallest bucket >= transfer_size is the > one incremented, so a 320KB IO increments the 512KB bucket. Since your > HW says it can only do a 320KB IO, there will never be a 1MB IO. > > You may want to instrument your HBA driver to see what is going on (ie, > why the max_hw_sectors_kb is < 1024). > > Kevin > > > Kevin Hildebrand wrote: >> Hi, I'm having some performance issues on my Lustre filesystem and it >> looks to me like it's related to I/Os getting fragmented before being >> written to disk, but I can't figure out why. This system is RHEL5, >> running Lustre 1.8.4. >> >> All of my OSTs look pretty much the same- >> >> read | write >> pages per bulk r/w rpcs % cum % | rpcs % cum % >> 1: 88811 38 38 | 46375 17 17 >> 2: 1497 0 38 | 7733 2 20 >> 4: 1161 0 39 | 1840 0 21 >> 8: 1168 0 39 | 7148 2 24 >> 16: 922 0 40 | 3297 1 25 >> 32: 979 0 40 | 7602 2 28 >> 64: 1576 0 41 | 9046 3 31 >> 128: 7063 3 44 | 16284 6 37 >> 256: 129282 55 100 | 162090 62 100 >> >> >> read | write >> disk fragmented I/Os ios % cum % | ios % cum % >> 0: 51181 22 22 | 0 0 0 >> 1: 45280 19 42 | 82206 31 31 >> 2: 16615 7 49 | 29108 11 42 >> 3: 3425 1 50 | 17392 6 49 >> 4: 110445 48 98 | 129481 49 98 >> 5: 1661 0 99 | 2702 1 99 >> >> read | write >> disk I/O size ios % cum % | ios % cum % >> 4K: 45889 8 8 | 56240 7 7 >> 8K: 3658 0 8 | 6416 0 8 >> 16K: 7956 1 10 | 4703 0 9 >> 32K: 4527 0 11 | 11951 1 10 >> 64K: 114369 20 31 | 134128 18 29 >> 128K: 5095 0 32 | 17229 2 31 >> 256K: 7164 1 33 | 30826 4 35 >> 512K: 369512 66 100 | 465719 64 100 >> >> Oddly, there's no 1024K row in the I/O size table... >> >> >> ...and these seem small to me as well, but I can't seem to change them. >> Writing new values to either doesn't change anything. >> >> # cat /sys/block/sdb/queue/max_hw_sectors_kb >> 320 >> # cat /sys/block/sdb/queue/max_sectors_kb >> 320 >> >> Hardware in question is DELL PERC 6/E and DELL PERC H800 RAID >> controllers, with MD1000 and MD1200 arrays, respectively. >> >> >> Any clues on where I should look next? >> >> Thanks, >> >> Kevin >> >> Kevin Hildebrand >> University of Maryland, College Park >> Office of Information Technology >> _______________________________________________ >> Lustre-discuss mailing list >> [email protected] >> http://lists.lustre.org/mailman/listinfo/lustre-discuss >> > > _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
