Guys,

 

Tried researching this myself but I have failed  I have a 3 in 2 sata backplane installed with hotswap capabilities.  I wanted to know if with the hotswapping feature you can really pull out the drive while the machine is on(I'm guess you will at least need to stop the unRaid array), but will that  be the only required step?  I should be able to pull out the drive, take a look at it, and push it back in and then re-start the array all while my machine is still on..correct?  Can I do it the same way if I needed to replace a drive as well(stop the array and simply replace the drive without turning off the machine?) .  Thanks for the adivce guys...I'm getting the hang of this, its just taking some time...

Hopefully, you will get more expert answers than this, but I can comment at least that a feature like hot swap requires both hardware and software support, in order to work correctly.  I don't believe that unRAID has hot swap capabilities built into the software.

 

Therefore you are absolutely correct, that you should always stop the array first.  If you don't, then unRAID will probably consider the drive failed, and disable it, requiring a rebuild of that drive or the parity drive.

 

I am also not completely confident that unRAID or the kernel will properly assign the same device ID when the drive is re-inserted.  So you should consider this a test, of an untried and risky procedure.  Please let us know what happens.

 

As for replacing a drive, I can't see any reason NOT to turn off the machine, so much safer.  Just because you can replace a drive without turning the power off does not mean you should.  I cannot see any advantages, and I *can* see possible problems.  (I could be wrong, and someone will correct me.)

The only benefit of hotswapping is the ability to continue to use your device while you replace parts.  That is a good thing in a production IT environment where taking down, for example, the corporate email server for even 15 minutes is unacceptable, but just silly for home.  If your spouse or child complains that much about missing their movie for 15 minutes, you may want to consider replacing them.

 

 

Bill

 

 

Unless you have specific hardware and software support, hot swapping is not recommended with unRAID.

 

Usually hot swapping requires a software driver with intelligence to handle a swapped drive.

Hardware with electrical capability and a controller with intelligence to handle a swapped drive.

 

The real issue is informing the kernel a new drive has been installed, then dealing with it.

 

With the 3WARE controllers, you would run this command to off line the drive.

then another command to online a new drive.

Because the drive to kernel interface had an intermediate interface (the raid controller), this could be handled safely.

When the new drive was inserted, the driver would get an internal message, re sense the drive and you would be online.

If the drive was part of an array or mirror, the kernel would not even have to deal with the re - sense.

 

So I'm not sure how the current controllers would handle swapping a drive out from under them.

 

At least with  unraid, You would have to stop the array, swap the drive, see that the new drive and geometry were sensed, then restart the array.

There would have to be manual intervention to start the rebuild.

 

It's possible, but probably not safe, Therefore I would recommend the conventional, Stop the array, Shutdown, change the drive power up, go to the interface and adjust.