Remove then re-add drive with content intact?

[JasonC]

I need to run a chkdsk on a few drives in my pool, and I'll need to have them be offline to do so. Rather then take the entire machine down, can I remove it, check all the check boxes, and then, after I run the repairs, if I re-add the disk to the pool, will the contents just get merged like it had never left?

Thanks!

[gtaus]

3 hours ago, JasonC said:

I need to run a chkdsk on a few drives in my pool, and I'll need to have them be offline to do so. Rather then take the entire machine down, can I remove it, check all the check boxes, and then, after I run the repairs, if I re-add the disk to the pool, will the contents just get merged like it had never left?

Thanks!

In theory, you should be able to run chkdsk on your drives without negatively affecting DrivePool. In fact, I have seen DrivePool recommend running chkdsk on HDDs if it detects some problems. In most cases, chkdsk will find and repair problems without any problems.

Having said that, I once ran chkdsk on a DrivePool HDD and chkdsk wiped out the directory on that HDD, so it was basically an empty disk after it ran its task. So those contents were gone from everything, including DrivePool. My lesson learned was that if I needed to run chkdsk on a DrivePool HDD, I will now empty the HDD to the pool using the remove command in DrivePool, and then run chkdsk on the HDD, fix any repairs, and then add that HDD back to DrivePool. This, of course, takes a lot longer to accomplish because the remove command in DrivePool can take hours and hours on a large drive. However, it takes me even longer to replace the contrents of a HDD if chkdsk blows its mind and essentially reformats the drive during the chkdsk task. When you tell Windows to automatically fix your HDD with chkdsk, you don't have any more control over what it does at that point.

I don't know if my answer is of any help, but I hope you heed the warning and don't experience data loss like I did. Chkdsk is a Windows task and has nothing to do with DrivePool. If chkdsk runs without any problems, all your data will still be there for DrivePool.

 

[JasonC]

Quote

Chkdsk is a Windows task and has nothing to do with DrivePool. If chkdsk runs without any problems, all your data will still be there for DrivePool.

Right, except the problem is chkdsk wants to occur on an underlyng disk (2 disks, actually), not the pool. And it wants to umount the disk to be able to perform fixes, i.e. I need to remove the disk from the pool, since it would be unmounted, or I need to have it do it at reboot before the disk is mounted and has files in use by the pool. Not all chkdsk operations can be performed on a mounted file system, basically.

So while it's not directly a DrivePool operation, because it's affecting underlying NTFS structures in a repair scenario, it impacts DrivePool.

 

[Shane]

gtaus is correct:

• if chkdsk unmounts the drive, Drivepool will notice the drive is missing and change the pool to read-only until the drive is remounted at which point the drive will merge back into the pool and the pool will become writeable again
• it is unlikely but if chkdsk goes wrong and effectively formats the drive, the pool will need to be told that the drive is permanently gone and whatever was only on that drive will be lost
• it is also unlikely but if chkdsk goes wrong and mangles the drive contents but the poolpart folder itself is intact enough for drivepool to recognise it, drivepool will attempt to merge it back into the pool which may result in conflicts

Protips:

• use Windows Disk Management to take one of the pool's other good drives offline first, that way your pool will stay read-only until you put the good drive back online and you can thus check the suspect drive for yourself whether chkdsk did its job properly before you toggle the good drive back online to make the pool writable again
• if you don't already have backups, you can also take advantage of this read-only state to backup the current contents of the hidden poolpart folder on the suspect drive to somewhere else before running the chkdsk