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Cache drive showing unmountable after trying to add a second cache drive?

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I have a a spare 7200RPM HD that has barely been used so I thought I'd add it to my array as a second cache drive to increase the cache capacity (only have a 120GB SSD now). Installed it and booted back up and everything seemed fine. That was until I added a slot on the cache drive page and assigned the drive to it. As soon as I did this I got an error message from "fix common problems" and the original drive has been unmountable.

 

I tried to do a file system check in maintenance mode and it fails without doing anything. I get this:

 

No valid Btrfs found on /dev/sdd1

Couldn't open file system

 

But what's strange is that the current cache drive is showing as "sdd" and not "sdd1" on the cache drive page. So is this the problem? If so how do I fix that? And if it isn't the problem, can I fix this without having to reformat?

 

If I do have to reformat it won't be the end of the world. I actually have a backup of the cache drive app data and docker. I just don't understand what the heck happened. Can I not add a second cache drive??

  • Community Expert

Was your original cache btrfs?

  • Author
7 minutes ago, johnnie.black said:

Was your original cache btrfs?

 

Yes

  • Community Expert
11 minutes ago, acurcione said:

But what's strange is that the current cache drive is showing as "sdd" and not "sdd1" on the cache drive page. So is this the problem?

No.

 

Post your diagnostics.

  • Community Expert
12 minutes ago, acurcione said:

I'd add it to my array as a second cache drive to increase the cache capacity (only have a 120GB SSD now)

 

btw, by default adding a second device won't increase capacity, it will add redundancy.

  • Author
3 minutes ago, johnnie.black said:

 

btw, by default adding a second device won't increase capacity, it will add redundancy.

 

Great. I guess I failed this task miserably! :)

  • Author
5 minutes ago, johnnie.black said:

 

btw, by default adding a second device won't increase capacity, it will add redundancy.

 

At this point should I just say the heck with it and use the newly added drive which is 1TB as cache and copy over my backup on to it? 

  • Community Expert
Just now, acurcione said:

 

At this point should I just say the heck with it and use the newly added drive which is 1TB as cache and copy over my backup on to it? 

 

If you need the space yes.

 

About your issue, are you sure your cache was btrfs? Click on it, change file system to auto and start the array.

  • Author
1 minute ago, johnnie.black said:

 

If you need the space yes.

 

About your issue, are you sure your cache was btrfs? Click on it, change file system to auto and start the array.

 

No, I wasn't sure. That's just what was showing after this happened. I did what you said and it came right up! And it's XFS. No idea why it changed to btfrs when I tried to add the second drive though.

 

And just so I'm clear, adding a second drive does NOT increase cache capacity so if that's what I'm after I should just replace the current one. Yes?

  • Community Expert

A cache pool requires btrfs, so when you change slots to more than 1 unRAID changes the fs to btrfs.

 

1 minute ago, acurcione said:

And just so I'm clear, adding a second drive does NOT increase cache capacity so if that's what I'm after I should just replace the current one. Yes?

 

By default no, it's raid1, it can be changed but don't really see the point in using a small SSD together with a large disk, if you need the space use the disk only, you can use this procedure to replace the current cache.

 

 

  • Author
Just now, johnnie.black said:

A cache pool requires btrfs, so when you change slots to more than 1 unRAID changes the fs to btrfs.

 

 

By default no, it's raid1, it can be changed but don't really see the point in using a small SSD together with a large disk, if you need the space use the disk only, you can use this procedure to replace the current cache.

 

 

 

Great. Thanks sir. Should have asked BEFORE trying this!

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