Hi,

I'm running unRAID-5.0rc11.

I had two 3TB disks precleared and assigned to disk1 and disk2, and the array was working fine (with no parity, so no protection).

Parity was not assigned yet because I wanted to copy a lot of data quickly, and build parity later (migrating from an old NAS).

I finished copying data (all of it just on disk1), and then I wanted to add the parity disk.

I had another 3TB disk precleared, and tried to assign it as parity, but unRAID didn't let me do it, because it seems the 3TB drive assigned to disk2 was *slightly* larger than the other two 3TB drives (about 1KB, which is weird considering all drives are identical WD RED models purchased together).

So I thought I would just swap between disk2 and the 3rd drive - unRAID didn't let me do it ("too many wrong and/or missing disks!").

Then I tried disconnecting the larger drive, so unRAID sees only two identical drives (one assigned to disk1, and one precleared), hoping that now unRAID would let me assign the precleared drive to disk2 - but still "too many wrong and/or missing disks!"...

 

Anyone has any idea on how I can make unRAID forget about the previous disk2 drive and just use the new one?

(obviously I don't care about the "lost data" on disk2, as there isn't any data and that disk)

If I can do that, I would be able to repeat preclear on the slightly larger drive and assign it to parity.

 

Thanks,

- Itamar.

because it seems the 3TB drive assigned to disk2 was *slightly* larger than the other two 3TB drives (about 1KB, which is weird considering all drives are identical WD RED models purchased together).

 

That's a serious issue, you'll want to look into HPA, it's a feature that some mother boards have which save a backup of their settings to the HDD, which, completely screws(better? Not sure if this is offensive) unraid over because of the changing sizes.

because it seems the 3TB drive assigned to disk2 was *slightly* larger than the other two 3TB drives (about 1KB, which is weird considering all drives are identical WD RED models purchased together).

 

That's a serious issue, you'll want to look into HPA, it's a feature that some mother boards have which save a backup of their settings to the HDD, which, completely **** unraid over because of the changing sizes.

Valid point, but please try to keep the language G rated. You are speaking to a large and diverse audience, and your point will be made much better without the coarse language.

because it seems the 3TB drive assigned to disk2 was *slightly* larger than the other two 3TB drives (about 1KB, which is weird considering all drives are identical WD RED models purchased together).

 

That's a serious issue, you'll want to look into HPA, it's a feature that some mother boards have which save a backup of their settings to the HDD, which, completely **** unraid over because of the changing sizes.

Valid point, but please try to keep the language G rated. You are speaking to a large and diverse audience, and your point will be made much better without the coarse language.

 

Normally I try to (on this forum), however, one slips out every once and awhile. Edited.

Normally I try to (on this forum), however, one slips out every once and awhile. Edited.

Thank you for editing your post, screwing up is normal every now and then. 

 

To more fully answer the OP's questions, HPA is most likely the cause, as Automatic said, and here is some more reading on the subject.

 

Also, before you jump in headfirst and start removing HPA's left and right, keep in mind that removing the HPA has the immediate effect of making the drive appear to be erased, as the file system markers are no longer at the same address. If you remove HPA from a drive, it will need to be rebuilt, so proceed very carefully so as not to lose data. If you remove HPA from two drives already in the protected array at the same time, you will lose data. It may be able to be recovered, but it's a pain. Also, you risk the data on your other drives if they were to happen to fail while you are rebuilding a disk.

 

I realize you don't have a protected array right now, but other people might find this post by searching, and I wanted to be thorough.

 

In your case, you need to find out which motherboard is causing the issue, and make it stop permanently. Then you can proceed to remove the HPA's and reformat the drives and copy your data back over. I think your plan of copying data without setting up parity is a mistake, because now is the time you want to find any errors or problems with the array, not after you have copied all your data and started using it for real.

 

If you are dead set on proceeding the quickest (not safest) way, you could just remove the HPA from the drive you want to assign as parity, make sure HPA isn't going to be readded, and go ahead with the parity build. You don't HAVE to remove HPA from the data drives, just the parity drive.

You can un-assign the old larger disk2, and then use the "Utils->New Config" to reset the configuration to where you can use the larger disk for parity.

 

As mentioned, there is a huge issue if there is an HPA on the disk.  Use

hdparm -N /dev/sdX

to determine the disk sizes of each of your disks.  It should tell you if an HPA is present.

 

Joe L.

Thanks for all the advice!

I've looked up on HPA (wasn't aware of the issue before..),

and found another thread (http://lime-technology.com/forum/index.php?topic=4194.msg37010#msg37010) linked from the topical index with information on how to remove HPA using hdparm.

So I used hdparm -N to diagnose that indeed HPA is enabled on the two "smaller" HDs, and not on the "larger" one,

then I used hdparm -N p### /dev/sdb to disable HPA on the precleared disk (the one that wasn't assigned to the array yet).

I verified HPA was disabled by resetting the server and using hdparm -N to check the status post-reset, which seemed OK.

Now I'm trying to assign the "fixed" disk as parity, but unRAID doesn't realize the size changed, and shows the same old size.

 

Do I need to rerun preclear after disabling HPA? or do something else?

 

Thanks,

- Itamar.

The most critical point to deal with before you proceed is to make sure you figure out how the drive got HPA'd. Do you know for certain how it happened?

The most critical point to deal with before you proceed is to make sure you figure out how the drive got HPA'd. Do you know for certain how it happened?

 

Well, the disks were precleared using a PC with Gigabyte mobo, so I guess this is how they got HPA'd.

The actual server has ASUS mobo.

Why is this critical to figure out?

The most critical point to deal with before you proceed is to make sure you figure out how the drive got HPA'd. Do you know for certain how it happened?

 

Well, the disks were precleared using a PC with Gigabyte mobo, so I guess this is how they got HPA'd.

The actual server has ASUS mobo.

Why is this critical to figure out?

 

Because every disk that you put into that system with the Gigabyte board will have HPA installed on it --- (probably as soon as the BIOS detects it)!!! 

 

Double check the BIOS for the Gigabyte board.  Many of the new boards don't have it.  Others will have it disabled by default (not yours obviously) and other have it enabled by default.

Thanks for all the advice!

I've looked up on HPA (wasn't aware of the issue before..),

Interesting reading, isn't it.

Do I need to rerun preclear after disabling HPA? or do something else?

Yes, it will not appear as a precleared disk if you do not.

 

Just be aware, that Gigabyte board will not be helping you unless you can disable the "feature" that copies its BIOS to the disk.

 

A little late on reporting this is solved, but better late than never :-)

 

My issue indeed was the Gigabyte MoBo I used to preclear the disks setting HPA.

I was not able to find a way to turn off the "feature" in the BIOS,

but the following workaround worked for me:

1. Connect a "dummy HD" as the first device on the mobo, and let the mobo set HPA on it (some spare HD laying around).

2. While the "dummy HD" connected, connect my "real HDs" (the 3TB disks I actually want to use).

3. Use "hdparm" to disable HPA on the "real HDs" (http://lime-technology.com/forum/index.php?topic=4194.msg37010#msg37010)

4. VERY IMPORTANT! Restart the server, and use "hdparm" after restart to verify that HPA is indeed disable on the "real HDs" (I actually tried running preclear before restarting the server and noticed in the pre-report that the number of sectors was recognized as if HPA is still enabled!)

5. Rerun preclear on the "real HDs" with HPA disabled

 

Thanks again for the support and advice!