This might be a niche feature/request, but it would be a good feature if unraid supported hot swappable hard drive support. This feature would only be active once you have to stopped the array. When the array has stopped, only then you have the option in a button next to the disks to say 'stop and remove disk', for example. It would be good for those whose mobo's and disks support such a option, but unraid doesn't currently. I can understand their wouldn't be a need to implement this idea given the unraid OS only takes about 2 to 5 mins to initialize from a powered off state (if you ever had to replace a disk), but for those who wouldn't like to every switch off their server, it might have some use/benefit. Your opinions?

If the feature were there, I would use it.  However, I don't see it as much of a priority since, as you said, the shut down -> replace disk -> boot up process is pretty quick.

Hot swap support is available in Linux, but it is dependent on the CONTROLLER supporting it (most non-RAID controllers do not, and even a lot of RAID controllers do not support it either)

If the actual hardware were to be compatible (ie: controllers, addon cards, etc...), then your saying bubbaQ  that unraid should support it too? I was under the impression unraid didn't support this?

I'm taking a wild stab in the dark here, but you might be able to get "warm swap" functionality assuming you have a CONTROLLER that supports hot-swap:

 

1) stop the unRAID array

2) kill emhttp

3) hot plug the new drive into hot-swappable controller

4) start emhttp

5) make changes to unRAID array configuration

6) start unRAID array

I was under the impression unraid didn't support this?

 

It doesn't but you can stop the array, swap, and restart like BRiT described --- ASSUMING you have a controller that supports it, and you run the necessary commands to tell the system you are swapping a drive.  You also may have to unload and reload emhttp.

I was under the impression unraid didn't support this?

 

It doesn't but you can stop the array, swap, and restart like BRiT described --- ASSUMING you have a controller that supports it, and you run the necessary commands to tell the system you are swapping a drive.  You also may have to unload and reload emhttp.

You will need to kill and re-start emhttp.  From my own experience, I think it it only looks at the available drives when it starts up.  Unless things have changed, you will get it really confused otherwise, especially if linux switched device assignments on you.

I don't understand the purpose for such thing.

Because you'll have to start a parity check/rebuild every time you do it.  ???

 

I don't understand the purpose for such thing.

Because you'll have to start a parity check/rebuild every time you do it.

 

For one example, it would be useful in the event of a drive FAILURE of a system you don't want to shut down.

 

For example, I run some home automation and home security utilities on my unRAID box.  If a drive in the array fails, I have to shut down to replace it.  With a hot swap, I could unload emhttp, swap the failed drive, restart emhttp, and then the drive will rebuild.... all without shutting down my server.... so all the other apps continue to run (assuming they are not using files on the array).

I understand.

That is a good idea.

I have a warm spare hooked up via eSATA in a small external case with fan.  It's always on and in the go script I send the htparm command to spin it doen in 3 minutes.... it's normally spundown all the time.  I can deselect a failed drive by selecting this ext drive with the array stopped, then rebuild onto it.  The nice part is that I can do it remotely by remotedesktop into my desktop machine and then log onto the unraid web interface.

 

I should of introduced this idea with an example of how this would be useful, say we had the scenario below:

 

disk1 -> Parity

 

disk2, disk3, disk4 -> 'Movies' Share/Array

 

disk5, disk6, disk7 -> 'Music' Share/Array

 

disk9, disk10, disk11 -> 'TVShows' Share/Array

 

For argument sake, (if it were possible to group disks into a group array, Im not sure you can do this in unraid), say disk6 in the array 'Music' were to fail, and you don't want the 'Movies' and the 'TVShows' array to go down with it as their in use, keeping the whole unraid server running, you could stop just the 'Music' array, pull out faulty disk6, swap it with a new one, start the 'Music' array again, obviously it would need to rebuild 'disk6' from parity and within x amount of hours, the disk6 is ready and the 'Music' share/array is online again. I understand the unraid OS might require a overhaul to support such a feature, also it might be a niche feature given that if you wanted such an option, you'd invest into a corporate-style disk array/raid solution, but like Ive mentioned above, the idea of not disrupting the other group of disk arrays would be great given this scenario were to happen and some unraid users might actually have a use for this feature too. Also too, pending hardware support of the server itself too would be a requirement.

I should of introduced this idea with an example of how this would be useful, say we had the scenario below:

 

disk1 -> Parity

 

disk2, disk3, disk4 -> 'Movies' Share/Array

 

disk5, disk6, disk7 -> 'Music' Share/Array

 

disk9, disk10, disk11 -> 'TVShows' Share/Array

 

For argument sake, (if it were possible to group disks into a group array, Im not sure you can do this in unraid), say disk6 in the array 'Music' were to fail, and you don't want the 'Movies' and the 'TVShows' array to go down with it as their in use, keeping the whole unraid server running, you could stop just the 'Music' array, pull out faulty disk6, swap it with a new one, start the 'Music' array again, obviously it would need to rebuild 'disk6' from parity and within x amount of hours, the disk6 is ready and the 'Music' share/array is online again. I understand the unraid OS might require a overhaul to support such a feature, also it might be a niche feature given that if you wanted such an option, you'd invest into a corporate-style disk array/raid solution, but like Ive mentioned above, the idea of not disrupting the other group of disk arrays would be great given this scenario were to happen and some unraid users might actually have a use for this feature too. Also too, pending hardware support of the server itself too would be a requirement.

The feature you are requesting is to have multiple logical "arrays".  It has been brought  up before.

 

However... the unRAID array is completely available while rebuilding a drive.  You can read and write the failed drive after it fails and is taken off-line by unRAID, and during the rebuild of it.  You can also read and write to any of the other drives during those times.    If you were not paying attention to the management console you might not even notice the disk failure.

 

The only time you cannot access the failed drive is when you stop the array and power down to replace it.  Once you press "Start" to begin the rebuilding of the replaced drive everything is available.

 

Once, long ago I simulated that on my array playing 4 different DVD ISO images from a disk being rebuilt, while it was being rebuilt.  worked just fine.

That grant Joe L, it seems this feature could be implemented then, pending hardware support and proper testing/enablement in unraid. Again, probably would be a niche feature, but you wouldn't have any down time to stop the whole array of all your disks just to remove the faulty drive. I dont recall that you can create logical array/group of disks in unraid (well not in the webgui, maybe it could be coded in the CLI). Is this a correct statement to make? Sorry, I'm still learning unraid, hence all the questions I post. Thanks.

That grant Joe L, it seems this feature could be implemented then, pending hardware support and proper testing/enablement in unraid. Again, probably would be a niche feature, but you wouldn't have any down time to stop the whole array of all your disks just to remove the faulty drive. I dont recall that you can create logical array/group of disks in unraid (well not in the webgui, maybe it could be coded in the CLI). Is this a correct statement to make? Sorry, I'm still learning unraid, hence all the questions I post. Thanks.

As you said, hot-swap is a niche market (in the unRAID target market of home media storage).  The "md" driver is not coded to handle multiple logical arrays. I would think it would take a major re-write. 

 

There is only one array. It is coded to only support one array. Any drive you assign to the array is in the one-and-only array.  It is not a command line issue, it is very low level in the "md" driver.  You don't group them because there is only one group.

 

Joe L.