DrivePool+CloudDrive configuration question

[darkly]

I'm currently using a CloudDrive that is partitioned into many smaller parts and pooled together with DrivePool. The CloudDrive is encrypted and NOT set up to automatically mount when the OS loads. One downside of this is that if any applications are expecting a directory to exist, it won't be able to find it until I unlock the CloudDrive and DrivePool picks up at least one partition. I have an idea on how to resolve this, but I'm not sure exactly how to implement it. I'm thinking that if I either add a local drive to the existing pool, or create a new pool consisting of just the local drive + the existing pool (nested), and somehow set the balancing rules so that the local drive is always 0% utilized, then 1) that pool would always be available to the system (at least once DrivePool services load), 2) once the CloudDrive is unlocked, the local drive (in the pool) would not be utilized at all, and 3) if the CloudDrive is NOT unlocked, then writes to the pool would be forced to the local drive, but immediately offloaded to the CloudDrive once it IS unlocked. Does this make sense? And how (if possible) could I configure DrivePool to do this?

[srcrist]

I'm not 100% positive on this, but I believe that once the cloud drive is added to the pool, if the system boots up and the drive is still locked, Drive Pool will see the locked drive as "unavailable" just like if you had a removable drive in your pool that was disconnected. That means that balancing would be disabled on the pool until all of the drives are available. It won't start rebalancing without the drive being unlocked, unless you remove the drive from the pool. It should be aware of all of the drives that comprise the pool, even if some  of the drives are missing. The information is duplicated to each drive. 

Bottom line: no special configuration should be necessary. DrivePool should function perfectly fine (accepting data to local drives) while the cloud drives are missing, and then balancing rules will be reapplied once the drives become available. Though, the part I'm not sure about is whether or not the pool will be placed into read-only mode as long as a drive is missing. It may simply not accept any written data at all--and, if that's the case, I'm not sure if there is a way to change that. You may just have to wait until all of the drives are available. 

[darkly]

3 hours ago, srcrist said:

I'm not 100% positive on this, but I believe that once the cloud drive is added to the pool, if the system boots up and the drive is still locked, Drive Pool will see the locked drive as "unavailable" just like if you had a removable drive in your pool that was disconnected. That means that balancing would be disabled on the pool until all of the drives are available. It won't start rebalancing without the drive being unlocked, unless you remove the drive from the pool. It should be aware of all of the drives that comprise the pool, even if some  of the drives are missing. The information is duplicated to each drive. 

Bottom line: no special configuration should be necessary. DrivePool should function perfectly fine (accepting data to local drives) while the cloud drives are missing, and then balancing rules will be reapplied once the drives become available. Though, the part I'm not sure about is whether or not the pool will be placed into read-only mode as long as a drive is missing. It may simply not accept any written data at all--and, if that's the case, I'm not sure if there is a way to change that. You may just have to wait until all of the drives are available. 

Thanks. I've actually tested having parts of a pool absent before and I'm pretty sure you can still write to the remaining drives. My problem is that once the cloud drive comes online, I don't want to simply "balance" the pool. I don't want the local disk(s) in the pool to be used at all. Ideally, once the CloudDrive comes back online, all data is taken off the local disks and moved to the CloudDrive. I'm just not sure how I'd configure that behavior to begin with. If the first part of what you said is correct (that balancing would be paused), then that's great, as that's exactly the behavior I'd want while the CloudDrive is not mounted, as I'd still want to be able to move files onto the pool's local disks (even though those local disks are somehow configured to hold 0% of the data once "balanced"). Any idea how to set up DrivePool to balance in this way?

[srcrist]

16 hours ago, darkly said:

Thanks. I've actually tested having parts of a pool absent before and I'm pretty sure you can still write to the remaining drives. My problem is that once the cloud drive comes online, I don't want to simply "balance" the pool. I don't want the local disk(s) in the pool to be used at all. Ideally, once the CloudDrive comes back online, all data is taken off the local disks and moved to the CloudDrive. I'm just not sure how I'd configure that behavior to begin with. If the first part of what you said is correct (that balancing would be paused), then that's great, as that's exactly the behavior I'd want while the CloudDrive is not mounted, as I'd still want to be able to move files onto the pool's local disks (even though those local disks are somehow configured to hold 0% of the data once "balanced"). Any idea how to set up DrivePool to balance in this way?

I *believe* you can use the SSD balancer to do this, maybe? The way the SSD balancer works is that if you have a drive marked as "SSD" it copies the data there FIRST, and then moves it to other drives during a balancing pass. Any drive can, in fact, be marked as "SSD." So this might work to move all of the data off of the local drives once the cloud drives are available.