Doing my first pre-clear. What settings are recommended to use?

When choosing "Clear Disk" I'm able to choose 1-3 cycles.

When choosing "Erase and Clear Disk", theres no option for cycles.

The disk is brand new.

Thanks

34 minutes ago, lbob said:

Doing my first pre-clear. What settings are recommended to use?

When choosing "Clear Disk" I'm able to choose 1-3 cycles.

When choosing "Erase and Clear Disk", theres no option for cycles.

The disk is brand new.

Thanks

Choose clear disk and however many cycles (I usually do 3). Erase and clear is for emptying a disk prior to disposal.

Be aware that depending on the size of the disk each cycle could take 3 - 5 days, maybe more.

4 minutes ago, wgstarks said:

Choose clear disk and however many cycles (I usually do 3). Erase and clear is for emptying a disk prior to disposal.

Be aware that depending on the size of the disk each cycle could take 3 - 5 days, maybe more.

Thank you

I am no longer working on this plugin. LT has taken over the maintenance and support. You will need to contact them about any issues or concerns you have. Future releases will come from them, and not me.

Hi I got redirected here after posting in the support forum.

I recently purchased a HDD and wanted to test for early failure, but no matter how many times I try to preclear the drive it keeps coming back with FAIL! Invalid Unraids MBR signature on 3ZGYASGZ (sdk). I'm using the latest version of the Unassigned Devices Preclear plugin (2028.08.20). The first time I tried preclearing I was using a USB dock and thought there might be an issue with the dock, so I tried putting the HDD in my server and rebooting it instead but I'm still running into this issue. This is being connected via Dell PERC H310 to a supermicro 16 bay SAS2 backplane.

This seems to happen right after it finishes zeroing the drives. See attached preclear logs.

preclear.txt

11 hours ago, bobokun said:

Hi I got redirected here after posting in the support forum.

I recently purchased a HDD and wanted to test for early failure, but no matter how many times I try to preclear the drive it keeps coming back with FAIL! Invalid Unraids MBR signature on 3ZGYASGZ (sdk). I'm using the latest version of the Unassigned Devices Preclear plugin (2028.08.20). The first time I tried preclearing I was using a USB dock and thought there might be an issue with the dock, so I tried putting the HDD in my server and rebooting it instead but I'm still running into this issue. This is being connected via Dell PERC H310 to a supermicro 16 bay SAS2 backplane.

This seems to happen right after it finishes zeroing the drives. See attached preclear logs.

preclear.txt

Can you also attach your diagnostics

2 hours ago, Squid said:

Can you also attach your diagnostics

unnas-diagnostics-20250903-2129.zip

"Erase and Clear Disk - random patterns are written to the disk and then zeroes are written.  This is a good choice for a disk to be discard to ensure all traces of files are removed."

This adds the unraid signature, I wanted a fully wiped disk. It should be noted. Actually, all of the details should be noted on the tool instead of needing to be found on the forum.

On 2/27/2022 at 9:55 AM, dlandon said:

You can follow the status of preclears in UD, on the UD Preclear page, or by hovering your mouse on the preclear icon in the Unraid footer.

I've used gfjardim's preclear many times. I think this is my first time using UD preclear.

I did find the Tools | Disk Utilities | Preclear page to monitor progress, but I'm not seeing anywhere that shows progress on the Unassigned Devices page and I don't see a preclear icon in the Unraid footer.

Have these been removed since this was released back in Feb 2022?
Are they no longer available in Unraid 7.x?
Am I just missing something?

I know preclear is no longer necessary, but I'm old school (UR 4.x days, even), and I like to run it. I've had one drive die during the preclear, so I find it useful. This plugin is appreciated!

On 8/11/2025 at 9:52 AM, dlandon said:

I am no longer working on this plugin. LT has taken over the maintenance and support. You will need to contact them about any issues or concerns you have. Future releases will come from them, and not me.

Also, is there a direct to LT support thread now, or do we just post a new question in the general support forum?
Maybe you should get this thread locked so goobers like me don't keep asking questions...

In my defense, the link from the plugins page does still link to this thread.

Edited October 16, 2025Oct 16 by Free Man

12 hours ago, Free Man said:

Also, is there a direct to LT support thread now, or do we just post a new question in the general support forum?

This is still the UD plugin support thread.

I solved this by just not using the preclear plugin and allowing unraid to do it during disk add. 🤷‍♂️

Did my best to make sure I'm following etiquette with this post... I tried preclearing two new 12TB HDD at the same time and one of them came back with this? it looks like there's still full I/O happening based on the activity listed in the Main tab/unassigned devices. The plugin page shows "Preclear Finished Successfully!" but the other disk entered the zero-ing stage while this one did not. i'm unable to do anything with the disk as it looks like it's still being cleared and the "Preclear" button is grayed out. Tried chatgpt, but wasn't confident in the responses and wasn't able to find any references to this anywhere else. I'm assuming this isn't a disk issue? Do I need to abort this somehow, or will the reading of the disk stop at some point? Any help is appreciated!

Oct 21 12:27:48 preclear_disk_ZRT2HR1V_39819: Preclear Disk Version: 1.0.31 Oct 21 12:27:48 preclear_disk_ZRT2HR1V_39819: Disk size: 12000138625024 Oct 21 12:27:48 preclear_disk_ZRT2HR1V_39819: Disk blocks: 2929721344 Oct 21 12:27:48 preclear_disk_ZRT2HR1V_39819: Blocks (512 bytes): 23437770752 Oct 21 12:27:48 preclear_disk_ZRT2HR1V_39819: Block size: 4096 Oct 21 12:27:48 preclear_disk_ZRT2HR1V_39819: Start sector: 0 Oct 21 12:27:50 preclear_disk_ZRT2HR1V_39819: Pre-read: pre-read verification started 1 of 5 retries... Oct 21 15:33:40 preclear_disk_ZRT2HR1V_39819: Pre-Read: progress - 25% read @ 262 MB/s Oct 21 18:55:28 preclear_disk_ZRT2HR1V_39819: Pre-Read: progress - 50% read @ 232 MB/s Oct 21 18:57:01 preclear_disk_ZRT2HR1V_39819:  Oct 21 18:57:01 preclear_disk_ZRT2HR1V_39819: malloc: jobs.c:1475: assertion botched Oct 21 18:57:01 preclear_disk_ZRT2HR1V_39819: free: called with unallocated block argument Oct 21 18:57:01 preclear_disk_ZRT2HR1V_39819: Aborting.../usr/local/emhttp/plugins/unassigned.devices.preclear/scripts/preclear_disk.sh: line 595:  100 /   8045980 : syntax error: operand expected (error token is " 100 /   8045980 ") Oct 21 18:57:01 preclear_disk_ZRT2HR1V_39819: Preclear: total elapsed time: 6:29:13

Edited October 23, 2025Oct 23 by ianraff

FWIW, I'm not sure this works with 7.2.2.
I added a drive, ran this plugin, and 68 hours later was told the disk was clear.

Added the disk to my protected array... and a clearing option started.

On 11/22/2025 at 9:36 PM, scott919 said:

FWIW, I'm not sure this works with 7.2.2.
I added a drive, ran this plugin, and 68 hours later was told the disk was clear.

Added the disk to my protected array... and a clearing option started.

Seconding this, preclear was an effetcive waste of several days on 7.2.2. System started a clear anyway. The signature application step needs to be rechecked.

Edited November 27, 2025Nov 27 by Rekonnected

It's kind of disappointing LT ignoring this plugin if it's going to take them over

Can someone please post the output from fdisk -l /dev/sdX after the preclear is done.

2 hours ago, JorgeB said:

Can someone please post the output from fdisk -l /dev/sdX after the preclear is done.

No longer needed, I did some testing and it turns out the problem is not the plugin, it's a bug in Unraid 7.2.

I'll report the issue to LT, but for now with 7,2, it will only detect the erased signature if you reboot after preclearing the disk and before adding it to the array, or it will clear the disk again.

Was wondering why a unraid clear started on a pre-cleared disk....really wish I had come upon this sooner - hope this gets sorted out in the next version :)

19 hours ago, JorgeB said:

No longer needed, I did some testing and it turns out the problem is not the plugin, it's a bug in Unraid 7.2.

I'll report the issue to LT, but for now with 7,2, it will only detect the erased signature if you reboot after preclearing the disk and before adding it to the array, or it will clear the disk again.

There also doesn't seem to be a way to follow preclear progress.

It's been a while since I last used preclear but isn't this supposed to link to a progress window?

Preclear should be running but I can't open the window.

47 minutes ago, wgstarks said:

It's been a while since I last used preclear but isn't this supposed to link to a progress window?

You have to go to tools->preclear to see status, was removed from here a while ago sadly...

7 minutes ago, Kilrah said:

You have to go to tools->preclear to see status, was removed from here a while ago sadly...

☹️

On 11/30/2025 at 6:56 PM, JorgeB said:

No longer needed, I did some testing and it turns out the problem is not the plugin, it's a bug in Unraid 7.2.

I'll report the issue to LT, but for now with 7,2, it will only detect the erased signature if you reboot after preclearing the disk and before adding it to the array, or it will clear the disk again.

I'm curious, do you know why this happens (in technical terms) ?

2 hours ago, Rysz said:

I'm curious, do you know why this happens (in technical terms) ?

Not really, I assume the GUI is using some old disk info and not refreshing to get the current one, since it also happens the other way around, i.e., if you boot with a precleared disk and then format it before adding it to the array, it will still be detected as precleared.

Hi there! I recently purchased a new 14 TB WD Red Pro hard drive, but I’m having trouble performing a Pre-Read check. It’s strange that It failed immediately. I’ve tried restarting my PC, changing the SATA port, but the issue persists after three attempts. I’m curious to know if you think my drive is failing or if there’s something else going on. (I’ve never formatted my drive before.) Thanks for your help!

(sdd)

tower-diagnostics-20251205-2304.zip

tower-diagnostics-20251205-2304.zip

Edited December 6, 2025Dec 6 by Ben9

Device dropped offline. This is typically a power/connection issue. Replace or swap the cables and try again; if it's the same, it may be the disk.