Cache replacement

[Galileo]

On 7/18/2016 at 4:46 AM, JorgeB said:

How do I replace/upgrade a cache pool disk?

 

NOTE: currently broken on v6.9.x

 

A few notes:

-unRAID v6.4.1 or above required, upgrade first if still on an older release.

-Always a good idea to backup anything important on the current cache in case something unexpected happens

-This procedure assumes you have enough ports to have both the old and new devices connected at the same time, if not you can use this procedure instead.

-Current cache disk filesystem must be BTRFS, you can’t directly replace/upgrade an XFS or ReiserFS disk.

-On a multi device pool you can only replace/upgrade one device at a time.

-You can directly replace/upgrade a single btrfs cache device but the cache needs to be defined as a pool, you can still have a single-device "pool" if the number of defined cache slots >= 2

-You can't directly replace an existing device with a smaller one, only one of the same or larger size, you can add one or more smaller devices to a pool and after it's done balancing stop the array and remove the larger device(s) (one at a time if more than one), obviously only possible if data still fits on the resulting smaller pool.

 

 

Procedure:

 

• stop the array
• on the main page click on the cache device you want to replace/upgrade and select the new one from the drop down list (any data on the new device will be deleted)
• start the array
• a btrfs device replace will begin, wait for cache activity to stop, the stop array button will be inhibited during the operation, this can take some time depending on how much data is on the pool and how fast your devices are.
• when the cache activity stops or the stop array button is available the replacement is done.
• if the new device is larger than the one being replaced you need to stop/re-start the array once the replacement is done for the new capacity to be available.

 

 

 

 

If I have a cache pool of 2 disks in btrfs raid 1, why do I need to have both the old drive and new drive connected to replace it? I don't have anymore sata ports available to do that. Since it's raid 1, can't I just shutdown and remove the old drive and out in the new one, then rebuild the raid set? Like if 1 drive were to fail. 

 

Thanks. 

[JorgeB]

NOTE: split from FAQ thread, please don't reply in that thread.

 

8 hours ago, Galileo said:

If I have a cache pool of 2 disks in btrfs raid 1, why do I need to have both the old drive and new drive connected to replace it? I don't have anymore sata ports available to do that. Since it's raid 1, can't I just shutdown and remove the old drive and out in the new one, then rebuild the raid set? Like if 1 drive were to fail. 

 

Thanks. 

If the pool is raid1 you can first remove one device then add anther one.