(SOLVED) Recovering data from cache drive

[geech]

Hi All.

 

Apologies if this has been asked and answered before - I did a search but could not find anything that helped.

 

I've been using Unraid for the last month or two and have loved it, but tonight I've managed to lose some data from my cache drive.

 

I have a PCiE card which contains 4 SSD's - one of which I had configured as a cache drive (The other 3 were previously unassigned). I've been receiving a number of SMART errors about the drive, so I thought I would configure cache to use one of the other drives on this card.

 

My config previously had drive sdd configured as a single cache drive. The change I made was to change this to use drive sde instead

 

Of course, I didn't bother reading any help files or wiki pages - and just went ahead and stopped the array changed the drive assigned as the cache drive. Upon restarting the array, I've now discovered I've lost all of my docker containers. When I go to the docker page, and click "Add Container" I've now got a drop-down for "Templates" which contains all of the containers I previously had installed. They do contain the settings for things like host paths, and keys, and appear to be set to what I had previously set - however when I install the app and check the WebUI I've lost all of the config settings within the application. I'm mainly using containers for media, so I have Sonarr, Radarr, Plex and a few others installed - and when I check Sonarr for instance, I no longer have anything configured.

 

When I stop the array, and try to configure it to use sdd as the cache drive again, I get the warning "All existing data on this device will be OVERWRITTEN when array is Started" - so I have no re-started the array using this drive as cache.

 

I had a fairly "default" install, and I was under the impression that being a cache drive meant it didn't really contain any share data. I was not aware that it contained any real data like docker shares. My question is, is there any way for me to recover all of the previous container information? Either by "recovering" the old cache drive without it being formatted, or re-installing apps on the new one. I'd like to not have to reconfigure the apps themselves.

 

I've attached a screenshot of my dashboard, and can upload diag files if it will help - but I'm hoping this is a fairly straightforward noob question.

 

 

Edited April 6, 2019 by geech
My question has been answered, and my issue resolved

[trurl]

Your use of the device identifiers sdd,sde is not generally useful, since these are not necessarily the same from one boot to the next. Unraid identifies disks by their serial number,

 

Is one of the Unassigned Devices your former cache disk?

 

Go to Tools - Diagnostics and attach the complete diagnostics zip file to your next post.

[JorgeB]

4 hours ago, geech said:

When I stop the array, and try to configure it to use sdd as the cache drive again, I get the warning "All existing data on this device will be OVERWRITTEN when array is Started" - so I have no re-started the array using this drive as cache.

Start the array without any cache device assigned to make Unraid "forget" current cache config, then stop array, assign old cache device and start the array.

[geech]

18 hours ago, johnnie.black said:

Start the array without any cache device assigned to make Unraid "forget" current cache config, then stop array, assign old cache device and start the array.

Thankyou so much - this worked perfectly. I think I'll do some more reading about how the cache disk works to avoid losing this again!

 

Thanks again!

[UnInfamous]

On 4/5/2019 at 6:54 AM, johnnie.black said:

Start the array without any cache device assigned to make Unraid "forget" current cache config, then stop array, assign old cache device and start the array.

This is amazing. I can’t believe doing this was so simple!

 

I am OCD when it comes to the alignment of my drives, when I would get (a) new drive(s), I would want to put them at the end of my 10TB drive section, but before my 4TB drive section. So I would rebuild data onto the new one, preclear, and move the previous top 4TB to the end of the array.

 

Now if I understand this properly, all I have to do in the future is:

1. Stop the array.

2. Unassign the drive that’s in the spot I want the new one.

3. Start the array.

4. Stop the array.

5. Assign the new drive in the old spot, and the moved drive at the end.

6. Start the array.

7. Parity check.

 

Fantastic. Am I missing anything, or does this method only work with Cache pools?
 

Can’t believe @SpaceInvaderOne hasn’t covered this in a video.

[JorgeB]

3 minutes ago, TheInfamousWaffles said:

Fantastic. Am I missing anything, or does this method only work with Cache pools?

That is just for the cache pool, but if you're using single parity you can move drives around after doing a new config while keeping parity valid.

[UnInfamous]

Ahh. I’ve got dual parity. Suppose I could just drop the second parity drive and parity rebuild when done.

 

I was thinking I had to do new config, but it’s scary, and way too much data to risk. There are no real videos going into a lot of detail about using it.

[JorgeB]

6 minutes ago, TheInfamousWaffles said:

I was thinking I had to do new config, but it’s scary, and way too much data to risk.

There's no risk in doing a new config, unless you assign a data disk as parity, and it's even more safe lately with the keep assignments option.

 

You could do a new config, re-order data drives as you wish, unassign parity2, check parity is already valid before starting the array and it would be protected since start, then after starting the array at least one time re-add parity2 and sync it.

[UnInfamous]

That’s fair. Suppose it was just hard to visualize what it means and what’s going on in the background.

[trurl]

23 hours ago, TheInfamousWaffles said:

That’s fair. Suppose it was just hard to visualize what it means and what’s going on in the background.

If you are talking about New Config, nothing going on. All it means is you can assign any disks any way you want, and then optionally (and by default) rebuild parity. Nothing happens to any of your other settings, and nothing happens to your data unless

23 hours ago, johnnie.black said:

you assign a data disk as parity