I have grown a raid5 over the years with drives and resized partitions, now I have upgraded to centos7 (from centos5). And I have the impression the speed is not what it used to be. Can this be because of some missalignment? How can this be verified? If I monitor the individual disks with dstat it reads the raid drives at very low speeds dd if=/dev/md21 of=/dev/null bs=1M count=1500 iflag=direct 1500+0 records in 1500+0 records out 1572864000 bytes (1.6 GB) copied, 19.5879 s, 80.3 MB/s 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 256k 0 : 320k 0 : 320k 0 : 192k 0 : 256k 0 : 320k 0 : 256k 0 4672k 0 :4672k 0 :4672k 0 :4800k 0 :4672k 0 :4672k 0 :4736k 0 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 13M 0 : 13M 0 : 13M 0 : 13M 0 : 13M 0 : 13M 0 : 13M 0 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 19M 0 : 19M 0 : 19M 0 : 19M 0 : 19M 0 : 19M 0 : 19M 0 9984k 0 :9792k 0 :9792k 0 :9792k 0 :9984k 0 :9984k 0 :9856k 0 13M 0 : 13M 0 : 13M 0 : 13M 0 : 13M 0 : 13M 0 : 13M 0 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 12M 0 : 12M 0 : 12M 0 : 12M 0 : 12M 0 : 12M 0 : 12M 0 7872k 0 :7744k 0 :7808k 0 :7744k 0 :7936k 0 :7744k 0 :7744k 0 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 : 11M 0 19M 0 : 19M 0 : 19M 0 : 19M 0 : 19M 0 : 19M 0 : 19M 0 7488k 0 :7360k 0 :7296k 0 :7360k 0 :7296k 0 :7296k 0 :7296k 0 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 : 10M 0 14M 0 : 14M 0 : 14M 0 : 14M 0 : 14M 0 : 14M 0 : 14M 0 9472k 0 :9536k 0 :9536k 0 :9536k 0 :9472k 0 :9536k 0 :9472k 0 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 When I test the individual disks with for disk in sdm sdl sdi sde sdk sdf sdd;do `dd if=/dev/$disk of=/dev/null bs=1M count=1500 iflag=direct &` ;done [root@san2 ~]# 1500+0 records in 1500+0 records out 1572864000 bytes (1.6 GB) copied, 8.96022 s, 176 MB/s 1500+0 records in 1500+0 records out 1572864000 bytes (1.6 GB) copied, 9.59289 s, 164 MB/s 1500+0 records in 1500+0 records out 1572864000 bytes (1.6 GB) copied, 10.0863 s, 156 MB/s 1500+0 records in 1500+0 records out 1572864000 bytes (1.6 GB) copied, 10.5833 s, 149 MB/s 1500+0 records in 1500+0 records out 1572864000 bytes (1.6 GB) copied, 10.6084 s, 148 MB/s 1500+0 records in 1500+0 records out 1572864000 bytes (1.6 GB) copied, 11.0205 s, 143 MB/s 1500+0 records in 1500+0 records out 1572864000 bytes (1.6 GB) copied, 11.3199 s, 139 MB/s 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 4096k 0 :5120k 0 : 32M 0 : 512k 0 : 29M 0 : 35M 0 :5120k 0 62M 0 : 51M 0 : 157M 0 : 145M 0 : 144M 0 : 153M 0 : 38M 0 153M 0 : 148M 0 : 158M 0 : 174M 0 : 135M 0 : 151M 0 : 150M 0 152M 0 : 144M 0 : 154M 0 : 179M 0 : 150M 0 : 146M 0 : 149M 0 149M 0 : 147M 0 : 155M 0 : 186M 0 : 148M 0 : 155M 0 : 157M 0 156M 0 : 128M 0 : 154M 0 : 188M 0 : 136M 0 : 153M 0 : 155M 0 159M 0 : 136M 0 : 157M 0 : 206M 0 : 147M 0 : 155M 0 : 151M 0 153M 0 : 147M 0 : 162M 0 : 153M 0 : 144M 0 : 127M 0 : 147M 0 153M 0 : 138M 0 : 159M 0 : 153M 0 : 134M 0 : 145M 0 : 146M 0 147M 0 : 144M 0 : 154M 0 : 116M 0 : 144M 0 : 153M 0 : 143M 0 154M 0 : 150M 0 : 60M 0 : 0 0 : 141M 0 : 131M 0 : 153M 0 61M 0 : 147M 0 : 0 0 : 0 0 : 51M 0 : 0 0 : 109M 0 0 0 : 17M 0 : 0 0 : 0 0 : 0 0 : 0 0 : 0 0 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -. F1 Outsourcing Development Sp. z o.o. Poland t: +48 (0)124466845 f: +48 (0)124466843 e: marc@xxxxxxxxxxxxxxxxx -- 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
