Hi, I do have _great_ performance troubles with software raid0 with 2.6.12 to .15. I have not tried earlier 2.6's, but 2.4 (tested up to 2.4.24) do it right. In fact, mdraid0 over 2 rather old 9G scsi disks here in my home server show same throughput as a single drive. I did try to tune readahead, tune various proc settings, used reiserfs and xfs or mdadm with different settings -- nothing helped. I'm clueless. ===================================== 0000:01:00.0 SCSI storage controller: Adaptec AIC-7861 (rev 03) scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 7.0 aic7860: Ultra Single Channel A, SCSI Id=7, 3/253 SCBs Vendor: IBM Model: DDRS-34560 Rev: S97B Type: Direct-Access ANSI SCSI revision: 02 scsi0:A:0:0: Tagged Queuing enabled. Depth 64 target0:0:0: Beginning Domain Validation target0:0:0: FAST-20 SCSI 20.0 MB/s ST (50 ns, offset 15) target0:0:0: Domain Validation skipping write tests target0:0:0: Ending Domain Validation Vendor: IBM Model: DNES-309170 Rev: SA30 Type: Direct-Access ANSI SCSI revision: 03 scsi0:A:1:0: Tagged Queuing enabled. Depth 80 target0:0:1: Beginning Domain Validation target0:0:1: FAST-20 SCSI 20.0 MB/s ST (50 ns, offset 15) target0:0:1: Domain Validation skipping write tests target0:0:1: Ending Domain Validation Vendor: IBM Model: DNES-309170 Rev: SA30 Type: Direct-Access ANSI SCSI revision: 03 scsi0:A:2:0: Tagged Queuing enabled. Depth 80 target0:0:2: Beginning Domain Validation target0:0:2: FAST-20 SCSI 20.0 MB/s ST (50 ns, offset 15) target0:0:2: Domain Validation skipping write tests target0:0:2: Ending Domain Validation ===================================== md4 : active raid0 sdc8[1] sdb8[0] 9542400 blocks 64k chunks /dev/md4 /home xfs rw,noatime,logbufs=8,sunit=128,swidth=256 /dev/sdc8: Timing cached reads: 340 MB in 2.00 seconds = 170.00 MB/sec Timing buffered disk reads: 56 MB in 3.12 seconds = 17.95 MB/sec /dev/sdb8: Timing cached reads: 344 MB in 2.01 seconds = 171.14 MB/sec Timing buffered disk reads: 54 MB in 3.01 seconds = 17.94 MB/sec /dev/md4: Timing cached reads: 344 MB in 2.01 seconds = 171.14 MB/sec Timing buffered disk reads: 50 MB in 3.07 seconds = 16.29 MB/sec ===================================== short vmstat 1 output running sequential writes with tiotest -f64 on 2.6.15(-cks3): 3 0 61020 52928 2132 125236 0 0 0 0 163 403 0 0 100 0 2 0 61020 53348 2132 125236 0 0 0 11 157 406 0 0 100 0 13 0 61020 10868 2132 167020 0 0 8 47093 157 376 1 63 36 0 2 3 61020 3716 2116 172980 0 84 0 63761 163 1982 3 71 0 26 3 3 61020 2500 2116 174176 0 0 0 17980 161 1179 0 30 0 70 2 3 61020 2404 2116 174252 0 0 0 6694 155 686 0 10 0 90 X 2 3 61020 2404 2116 174252 0 0 0 0 168 413 0 0 0 100 X 3 2 61020 2228 2116 174260 0 0 0 0 162 425 0 0 0 100 X disk 3 2 61020 2600 2120 174260 0 0 4 0 150 407 0 0 0 100 X use 2 2 61020 3264 2120 175196 0 0 0 5283 158 423 1 1 21 77 X 2 1 61020 3752 2120 174004 0 0 8 42110 177 2036 0 64 0 36 3 0 61020 3752 2120 174004 0 0 0 5 161 399 0 0 65 35 Tiotest results for 4 concurrent io threads: ,-----------------------------------------------------------------. | Item | Time | Rate | Usr CPU | Sys CPU | +---------------------+---------+-------------+---------+---------+ | Write 256 MBs | 15.4 s | 16.648 MB/s | 3.1 % | 83.9 % | | Random Write 16 MBs | 11.1 s | 1.413 MB/s | 0.2 % | 6.6 % | | Read 256 MBs | 19.4 s | 13.166 MB/s | 0.9 % | 28.6 % | | Random Read 16 MBs | 5.7 s | 2.731 MB/s | 0.0 % | 20.3 % | `-----------------------------------------------------------------' Tiotest latency results: ,------------------------------------------------------------------. | Item |Average latency |Maximum latency |% >2 sec |% >10 sec | +-------------+----------------+----------------+---------+----------+ | Write | 0.539 ms | 6917.495 ms | 0.00763 | 0.00000 | | Random Write| 0.135 ms | 71.025 ms | 0.00000 | 0.00000 | | Read | 0.997 ms | 1478.135 ms | 0.00000 | 0.00000 | | Random Read | 5.131 ms | 44.875 ms | 0.00000 | 0.00000 | |-------------+----------------+----------------+---------+----------| | Total | 0.875 ms | 6917.495 ms | 0.00360 | 0.00000 | `-------------+----------------+----------------+---------+----------' ritch - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
