unJim Posted April 23, 2017 Share Posted April 23, 2017 I have just precleared a disk to add to the array and noticed it was pretty quick; ############################################################################################################################ # # # unRAID Server Preclear of disk WDH2L9ZA # # Cycle 1 of 1, partition start on sector 64. # # # # # # Step 1 of 5 - Pre-read verification: [7:04:40 @ 157 MB/s] SUCCESS # # Step 2 of 5 - Zeroing the disk: [7:00:47 @ 178 MB/s] SUCCESS # # Step 3 of 5 - Writing unRAID's Preclear signature: SUCCESS # # Step 4 of 5 - Verifying unRAID's Preclear signature: SUCCESS # # Step 5 of 5 - Post-Read verification: [7:07:31 @ 155 MB/s] SUCCESS # # # # # # # # # # # # # # # ############################################################################################################################ # Cycle elapsed time: 21:13:06 | Total elapsed time: 21:13:07 # ############################################################################################################################ ############################################################################################################################ # # # S.M.A.R.T. Status default # # # # # # ATTRIBUTE INITIAL CYCLE 1 STATUS # # 5-Reallocated_Sector_Ct 0 0 - # # 9-Power_On_Hours 0 21 Up 21 # # 183-Runtime_Bad_Block 0 0 - # # 184-End-to-End_Error 0 0 - # # 187-Reported_Uncorrect 0 0 - # # 190-Airflow_Temperature_Cel 24 30 Up 6 # # 197-Current_Pending_Sector 0 0 - # # 198-Offline_Uncorrectable 0 0 - # # 199-UDMA_CRC_Error_Count 0 0 - # # # # # # # ############################################################################################################################ # SMART overall-health self-assessment test result: PASSED # ############################################################################################################################ --> ATTENTION: Please take a look into the SMART report above for drive health issues. --> RESULT: Preclear Finished Successfully!. So I ran the diskspeed.sh script to compare it to the other disks; diskspeed.sh for UNRAID, version 2.6.4 By John Bartlett. Support board @ limetech: http://goo.gl/ysJeYV Warning: Files in the array are open. Please refer to /tmp/lsof.txt for a list /dev/sdb (Disk 2): 113 MB/sec avg /dev/sdc (Disk 3): 120 MB/sec avg /dev/sdd (Cache): 470 MB/sec avg /dev/sde (Disk 1): 89 MB/sec avg /dev/sdf: 163 MB/sec avg /dev/sdg (Parity): 124 MB/sec avg To see a graph of the drive's speeds, please browse to the current directory and open the file diskspeed.html in your Internet Browser application. The new disk is sdf. As it is currently empty (and is the same size as the parity disk) I just wondered if there would be a speed advantage to be had by using the new disk as parity and moving the current parity to the array? Quote Link to comment
manifest3r Posted April 23, 2017 Share Posted April 23, 2017 Correct me if I'm wrong, but I believe your parity is as fast as your slowest disk. In this case, it would be sde. Quote Link to comment
unJim Posted April 23, 2017 Author Share Posted April 23, 2017 (edited) 37 minutes ago, manifest3r said: Correct me if I'm wrong, but I believe your parity is as fast as your slowest disk. In this case, it would be sde. I think you're correct as long as that disk is involved (during a parity check for example), disk 1 (sde) is actually only 2 tb, disk 2 and disk 3 are 3 tb and the parity disk is 4 tb. So halfway through the parity check disk 1 is finished with and things should speedup again with disk 2 now being the bottleneck. But let's say for example I want to write to disk 2 and 3 at the same time, disk 1 isn't even spun up, I guess disk 2 would still be the bottleneck. I'm also kind of thinking of the best way to lay them out for future upgrades, if I already have the fastest disk as parity, if / when I replace that smaller disks (because I want larger ones or one had failed) having the current speediest disk as parity would mean as I replace disks things would get incrementally faster. Writing this out has made me realise I'm probably overthinking it I'll just add it as a data disk! Edited April 23, 2017 by unJim Autocorrect. Quote Link to comment
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