Preclearing a new system

[cpugeek]

First please let me know if this thread needs to be moved to a different channel now onto my question.

 

I am building my first server here in the next week or so and the one thing I am trying to understand is when I initialize the array how long preclear will take. My parity drive will be a Seagate IronWolf 10TB ST10000VN0004 and the data drives will be 3 Seagate IronWolf 6TB ST6000VN0041. I am just trying to get a general idea of how long I should expect for my array to initialize and get the parity check done starting from the preclear step.

[whipdancer]

I know that there are changes in 6.4.1 around preclear, but I don't know what they entail.

My last drives were precleared using the preclear script (precleared before being added to the system).

My 3TB drives normally take about 70ish hours preclear (using the preclear script, 3 passes, mostly low power/green drives). Last 4TB drive took nearly 110 hours (it was a Blue drive and seemed much slower than normal).  Rough estimate for me would be about 80 hours to preclear a 10TB drive.

[cpugeek]

@whipdancer So you would say for the whole thing I can expect about 250 hours of preclear work to occur then? Or does the preclear work in parallel sorry for the noob question but its the first time I've done anything like this.

[whipdancer]

On 4/12/2018 at 6:16 PM, cpugeek said:

@whipdancer So you would say for the whole thing I can expect about 250 hours of preclear work to occur then? Or does the preclear work in parallel sorry for the noob question but its the first time I've done anything like this.

I can run multiple drives at the same time and it is faster than run them serially. Depending on the bus throughput for your controller you might not clear them each as quickly. For me, the clearing time was about 85 hours when I 2 drives at the same time (vs 1 drive taking about 70 hours). 

Just to clarify, I'm also running the preclear script 3 times on each drive as a torture test of sorts to help find any potentially bad drives.

Also, if you are running anything newer than unRaid 6.4.0, I believe there are issue running the preclear script.  I read something about it, but haven't looked into it yet and don't know for certain the issues.

[cpugeek]

@whipdancer Thank you for all the information. I really appricate the helping me start down my unraid journey.