File placement

[lee1978]

Hi,

 

Ok having made the jump to drivepool 2x from v1 I seem to have a little snag.

 

I set up a file placement rule for my music folder so it is all on 1 drive I have had problems with drives sleeping then having to be woke to play the next track on an album anyway having done that simple enough.

 

I hit the rebalance button it seems to do its stuff but now I get a warning saying "74.1gb could not be moved because a suitable destination could not be found. Make sure that you have enough disk space in order to satisfy your file placent rules and that they're not conflicting with other balancing settings.

 

Well I am stumped the drive I want it all on has 350gb of space which is plenty I haven't alterd any other settings since I installed v2 so I am stumped.

 

Lee

[Christopher (Drashna)]

Is duplication enabled for this folder? 

Could you post the rule you are using specifically?

And upload the logs from the system?

http://wiki.covecube.com/StableBit_DrivePool_2.x_Log_Collection

Just steps #5-7.

 

 

Also, are you on the 2.1.0.553 RC build?

[lee1978]

Hi Chris

 

Yes duplication is on and the rule is in the balancing section under file placement I just clicked on the music folder selected drive 1 only and clicked save then did rebalance it chugs away a little while but when it stops I get that warning

 

I will sort the logs later when I get home from work

[lee1978]

Hi

 

Think I know what the problem is the way a see a file placement rule would be I select my music folder select drive 1 all the files would be placed on that drive all the duplicated files placed on the other 13 drives.

 

however what it seems to do is place half the main files and half the duplicated files on drive 1 spreading the other halfs over the rest of the drives at least that is what the chart is telling me

 

Telling it to use 2 drives solves this half and half on each drive it also gets rid of the warning I have but either way means it has to wake up more that 1 drive to say play a music album which defeats the object in my opinion.

 

I don't think the file placement should even take into account the duplicated files apart from makeing sure none are the drive you want to use

 

Maybe Alex has some input on this

 

Lee

[Christopher (Drashna)]

Since this is definitely a complicated topic, I've flagged it for Alex, and will let him respond.

[Alex]

Lee,

 

In StableBit DrivePool there is no notion of "main" file parts and "duplicated" file parts. We just have some number of identical file parts for each file. Unduplicated files have one file part, and duplicated files have 2 or more. Where those file parts are placed can be controlled with file placement.

 

If you tell the balancing system to place a 2x duplicated folder on one drive, it will show you a warning that some file parts could not be placed on that drive. For a 2x duplicated folder, you need to select at least 2 drives in file placement in order to be able to satisfy those rules, or else the system will have to violate the rules.

 

But I still think that you can accomplish what you want.

 

If I understand you correctly, you want all of your music to be duplicated and to play from only the "first" file part. You can achieve this by using file placement to restrict the music folder to at least 2 drives and then to turn off Read Striping (under Pool Options -> Performance -> Read striping).

 

I've mentioned above that all file parts are the same, so how could there be a "first" file part?

 

For the purposes of read striping, when dealing with files that have > 1 file part, StableBit DrivePool's file system (CoveFS) does maintain a deterministic pool part order. In other words, the disks part of the pool are ordered in an invisible order and this order persists even after a reboot.

 

The point being, when read striping is off, and you open a duplicated file, the "first" file is always opened.