I've been seeing reports that using the preclear plugin to clear new disks is no longer necessary with unRaid 6.2 since unRaid will clear new disks in the background with the array online. I'm just curious what the procedure is for this? I don't see any info at all regarding this feature in the owners manual for unRaid 6. Are there any configurable options. Number of cycles, notifications, etc? I'm guessing multiple cycles may not be necessary, depending on what reports are generated, but notifications would be nice.

This is not a preclear.  The only difference from the past is that the array is started immediately, without waiting, while the clearing is performed in the background, then the drive is added and formatted.  In the past when you added a new disk (not Precleared), you would Start the array but the array would not actually start then, and you had to wait hours while it cleared the drive.

Yes. I knew this. My choice of words was incorrect and I've edited my original post. Is the entire clearing operation still completely done in the background without any notifications?

I doubt if few have tried it yet, we just discovered it, and it wasn't mentioned anywhere, but I suspect it's the same clearing as before.  The previous one would put a small notification in the bottom left corner, "Clearing 1%", "Clearing 2%", all the way to 100%, and possibly put the same in the syslog.

Thanks. You're the first person I've seen that has posted anything about this.

While this feature is indeed nice, and does indeed eliminate the primary reason for pre-clearing (to avoid the long downtime while a new disk is cleared); it does NOT provide the testing that the pre-clear utility does.

 

It's still a good idea to test a new drive before adding it to your array.    You can, however, simply use the manufacturer's diagnostics on another system for this purpose, since there's no longer any disadvantage to simply adding it to the array.    I like WD's Data Lifeguard utility for this purpose -- I always do a quick test; then an extended test; then a full write zeroes; and then repeat the quick & extended tests -- but you can use whichever utility you like the best.

 

There no options and no notifications, looks like this:

 

syslog:

Mar 29 21:40:11 Testv6 kernel: mdcmd (42): check CORRECT
Mar 29 21:40:11 Testv6 kernel: md: recovery thread: clear ...
Mar 29 21:40:11 Testv6 kernel: md: using 8192k window, over a total of 31266616 blocks.
Mar 29 21:41:21 Testv6 kernel: md: sync done. time=70sec
Mar 29 21:41:21 Testv6 kernel: md: recovery thread: completion status: 0

 

screen:

While this feature is indeed nice, and does indeed eliminate the primary reason for pre-clearing (to avoid the long downtime while a new disk is cleared); it does NOT provide the testing that the pre-clear utility does.

 

It's still a good idea to test a new drive before adding it to your array.    You can, however, simply use the manufacturer's diagnostics on another system for this purpose, since there's no longer any disadvantage to simply adding it to the array.    I like WD's Data Lifeguard utility for this purpose -- I always do a quick test; then an extended test; then a full write zeroes; and then repeat the quick & extended tests -- but you can use whichever utility you like the best.

 

I agree, but that's a topic that is being discussed elsewhere. I was just curious how the modified feature worked and didn't want to clutter that thread with OT posts. Hopefully the preclear plugin will be modified to be more about drive testing and less about clearing since the clearing function is no longer necessary.

There no options and no notifications, looks like this:

 

syslog:

Mar 29 21:40:11 Testv6 kernel: mdcmd (42): check CORRECT
Mar 29 21:40:11 Testv6 kernel: md: recovery thread: clear ...
Mar 29 21:40:11 Testv6 kernel: md: using 8192k window, over a total of 31266616 blocks.
Mar 29 21:41:21 Testv6 kernel: md: sync done. time=70sec
Mar 29 21:41:21 Testv6 kernel: md: recovery thread: completion status: 0

 

screen:

Thanks

... Hopefully the preclear plugin will be modified to be more about drive testing and less about clearing since the clearing function is no longer necessary.

Already being discussed in the preclear thread.