What's Negative Wasted GB

[MQMan]

SnapRAID status report:

   Files Fragmented Excess  Wasted  Used    Free  Use Name
            Files  Fragments  GB      GB      GB
   10002      50     242     1.0    1452     545  72% disk1
    8784      23     259       -    1064     810  56% disk2
   19765      45     107   -11.0    1385     599  69% disk3
    8729      17      38     0.0    1084     913  54% disk4
      19       0       0       -     192    1018  15% disk5    
       7       0       0       -      70    1397   4% disk6
 --------------------------------------------------------------------------
   47306     135     646     1.0    5250    5286  49%

And whats the difference between "-" and "0.0"

Cheers.

[Quaraxkad]

New in 8.0:

• In the "status" command the "Wasted" column now shows a negative number for the amount of space that you can still waste without filling up the parity.

[John]

This was my request: http://sourceforge.net/p/snapraid/discussion/1677233/thread/253fbb2f/

Mathematically it is the same formula all the time (before it was showing 0 instead of any negative). But in practical terms a very simple explanation goes like this:

• if you have the same size disks for parity then for (all or some) data disks you need to "reserve" some space on those data disks
• you can just keep quite a bit of space empty, you can play with quotas, partitioning (but this is tricky because you don't know in advance precisely how much space to reserve), etc
• but one good strategy in some cases is just to drop some data you don't want (or shouldn't have anyway) protected by snapraid. As you keep filling the disks with snapraid-protected data you can keep an eye on "Wasted", if there is enough left (well, anything negative is good but some tens of gigs is even better) then you won't have to worry about running out of parity.