File Placement behavior

[Dyleris]

Hi,

 

I am doing a trial of DrivePool (v2.1.1.561 on Win7 x64) and ran into the following situation:

 

1) Created a new pool, added a single 120 GB SSD to it (duplication is not enabled anywhere)

2) Moved 115 GB of data to the pool (it all went to the SSD, obviously)

3) Added an empty 1TB HDD to the pool

4) Moved a 50 GB VM folder to the pool. It ended up in the empty HDD (so far, so good)

5) Created a File Placement rule that the VM folder must be located within the SSD (for performance reasons). Also selected the 'Never allow...' option in the rule to absolutely force VM presence in the SSD

6) 'Re-balance' resulted in error "50 GB could not be moved...'

7) I restarted 'Re-balance' and, I suppose, 'Prevent Drive Overfill' balancer kicked in and freed 10% of SSD space (12 GB free now)

8) Another 'Re-balance' pass did move one file from the VM folder (sized 8 GB) to the SSD, but then failed with the message '42 GB could not be moved...'

9) Yet another 'Re-balance' activated 'Prevent Drive Overfill' and resulted in 12 GB of free SSD space

10) The final 'Re-balance' failed with the same '42 GB could not be moved...' as before, because the remainder of VM in the HDD consists of a single 42 GB file, which, of course, does not fit in the 12 GB of free space on the SSD

 

The engine seems incapable of the simple heuristic: 'Move out enough files from the almost-full SSD so that all 50 GBs of VM folder fits on the SSD - and then actually move those 50 GBs from the HDD to the SSD'. All the files on the SSD have checkmarks on both drives in 'File placements options', but the VM folder on the HDD has checkmark on the SSD checkbox only. It seems such a clear-cut case: 'those files can be anywhere, but this folder can only be here. Move some of those free files outside, and move this restricted folder in'

 

I've tried enabling and disabling various balancers, unmarking 'Settings'->'File placement settings' 1st and 3rd checkmarks, but the engine stubbornly refuses to make space and move the VM folder.

 

(Also tried to re-create the pool with steps #1-#3, then #5 (pre-create the Placement rule) and then #4 - which resulted in 'disk full' error while copying the 8 GB file. Apparently, the engine saw only 5 GB of free space on the mandated SSD and gave up)

 

So far, DrivePool seems sturdly built, KISS-adherent and useful - thus I am likely missing something obvious

 

Thanks for your time!

Edited September 30, 2015 by Dyleris

[Christopher (Drashna)]

You definitely dont' have 50GBs free on teh SSD, correct?

 

IF that's the case, then that's definitely the problem and yeah, it should be a bit more robust/intelligent than that. I've flagged that for Alex (The Developer).

 

However, in the meanwhile, depending on what you want, it may be worth checking out the "SSD Optimizer" balancer plugin. This used the "SSD" drives (which don't have to be SSDs) as a landing zone, and then moves the files off of them, onto the "Archive" drives.  It does this based on the balancer settings, and may work well for what you want.

https://stablebit.com/DrivePool/Plugins

 

I use this personally (even with File Placement Rules, so that shouldn't be an issue), though my system aggressively balances data off of the SSDs. 

 

And while I know it would be best to have it working without doing anything special, this is a solution that may work for you (and work well long term).