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reflect changes in the program usage and structure
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‎README.md‎

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@@ -12,29 +12,22 @@ This tool can approximately identify how much space will be freed when a snapsho
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This tool identifies all subvolumes of a btrfs filesystem. For each subvolume all file extents which are not inline are parsed and kept. All other items are ignored.
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Thus, we acquire a dictionary of chronologically ordered snapshots together with their set of file extents:
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Thus, we create a tree of extents & ranges together with the snapshots that use them:
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1. Snapshot 1
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1. file extent 1
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2. file extent 2
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1. file extent 1
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1. range1: [Snapshot 1, Snapshot 2]
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2. range2: [Snapshot 3]
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3. ...
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4. file extent n
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2. Snapshot 2
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1. file extent 1
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2. file extent 2
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3. ...
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4. file extent n
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3. Snapshot n
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1. ...
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Now, the actual disk size of Snapshot 1 is the size of the extents of snapshot 1 minus the common extents with snapshot 2. (Set(Snapshot1) - Set(Snapshot2))
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The actual disk size of Snapshot 2 is the size of the extents of snapshot 2 minus the common extents with snapshot 1 minus the common extents with snapshot 3. (Set(Snapshot2) - Set(Snapshot1)) - Set(Snapshot3)
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2. file extent 2
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3. range1: [...]
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4. range2: [...]
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Now, the actual disk size of Snapshot 1 can be extracted from each file extent
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## Usage:
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[python-btrfs](https://github.com/knorrie/python-btrfs) must be installed.
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`subvolume.py /path/to/btrfs <subvolume id to ignore1> <subvolume id to ignore2> ...`
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`subvolume.py -r <root tree, default 5> /path/to/btrfs/ <subvolume id to ignore1> <subvolume id to ignore2>`
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You can find suvolume ids by using:
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`btrfs subvolume list /path/to/btrfs`
@@ -44,90 +37,99 @@ You can find suvolume ids by using:
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`btrfs subvolume list /path/to/btrfs`:
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```
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ID 258 gen 14468 top level 5 path mydata
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ID 259 gen 14467 top level 5 path subvol_snapshots
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ID 258 gen 15649 top level 5 path mydata
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ID 259 gen 15651 top level 5 path subvol_snapshots
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ID 1949 gen 3785 top level 259 path subvol_snapshots/283/snapshot
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ID 2133 gen 5080 top level 259 path subvol_snapshots/435/snapshot
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ID 2395 gen 6616 top level 259 path subvol_snapshots/660/snapshot
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ID 2577 gen 8480 top level 259 path subvol_snapshots/783/snapshot
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ID 2694 gen 8781 top level 259 path subvol_snapshots/888/snapshot
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ID 3661 gen 10830 top level 259 path subvol_snapshots/1126/snapshot
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ID 3764 gen 11594 top level 259 path subvol_snapshots/1189/snapshot
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ID 3818 gen 11948 top level 259 path subvol_snapshots/1228/snapshot
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ID 3857 gen 12035 top level 259 path subvol_snapshots/1258/snapshot
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ID 3864 gen 12070 top level 259 path subvol_snapshots/1265/snapshot
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ID 3887 gen 12351 top level 259 path subvol_snapshots/1285/snapshot
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ID 3900 gen 12404 top level 259 path subvol_snapshots/1298/snapshot
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ID 3913 gen 12505 top level 259 path subvol_snapshots/1311/snapshot
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ID 3923 gen 12557 top level 259 path subvol_snapshots/1320/snapshot
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ID 3942 gen 12628 top level 259 path subvol_snapshots/1333/snapshot
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ID 3974 gen 13105 top level 259 path subvol_snapshots/1362/snapshot
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ID 4040 gen 13778 top level 259 path subvol_snapshots/1412/snapshot
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ID 4046 gen 13778 top level 259 path subvol_snapshots/1417/snapshot
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ID 4072 gen 13778 top level 259 path subvol_snapshots/1438/snapshot
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ID 4091 gen 13778 top level 259 path subvol_snapshots/1452/snapshot
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ID 4130 gen 13853 top level 259 path subvol_snapshots/1477/snapshot
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ID 4166 gen 14444 top level 259 path subvol_snapshots/1509/snapshot
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ID 4175 gen 14444 top level 259 path subvol_snapshots/1517/snapshot
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ID 4176 gen 14444 top level 259 path subvol_snapshots/1518/snapshot
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ID 4177 gen 14444 top level 259 path subvol_snapshots/1519/snapshot
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ID 4178 gen 14444 top level 259 path subvol_snapshots/1520/snapshot
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ID 4179 gen 14444 top level 259 path subvol_snapshots/1521/snapshot
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ID 4181 gen 14444 top level 259 path subvol_snapshots/1522/snapshot
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ID 4182 gen 14444 top level 259 path subvol_snapshots/1523/snapshot
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ID 4183 gen 14450 top level 259 path subvol_snapshots/1524/snapshot
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ID 4184 gen 14455 top level 259 path subvol_snapshots/1525/snapshot
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ID 4185 gen 14459 top level 259 path subvol_snapshots/1526/snapshot
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ID 4186 gen 14464 top level 259 path subvol_snapshots/1527/snapshot
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ID 4166 gen 14537 top level 259 path subvol_snapshots/1509/snapshot
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ID 4182 gen 14537 top level 259 path subvol_snapshots/1523/snapshot
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ID 4196 gen 14537 top level 259 path subvol_snapshots/1535/snapshot
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ID 4211 gen 14753 top level 259 path subvol_snapshots/1545/snapshot
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ID 4258 gen 15274 top level 259 path subvol_snapshots/1582/snapshot
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ID 4337 gen 15274 top level 259 path subvol_snapshots/1652/snapshot
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ID 4372 gen 15274 top level 259 path subvol_snapshots/1680/snapshot
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ID 4392 gen 15341 top level 259 path subvol_snapshots/1691/snapshot
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ID 4414 gen 15434 top level 259 path subvol_snapshots/1712/snapshot
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ID 4444 gen 15538 top level 259 path subvol_snapshots/1740/snapshot
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ID 4451 gen 15566 top level 259 path subvol_snapshots/1747/snapshot
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ID 4452 gen 15570 top level 259 path subvol_snapshots/1748/snapshot
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ID 4454 gen 15581 top level 259 path subvol_snapshots/1749/snapshot
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ID 4455 gen 15584 top level 259 path subvol_snapshots/1750/snapshot
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ID 4456 gen 15589 top level 259 path subvol_snapshots/1751/snapshot
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ID 4457 gen 15592 top level 259 path subvol_snapshots/1752/snapshot
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ID 4458 gen 15596 top level 259 path subvol_snapshots/1753/snapshot
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ID 4459 gen 15598 top level 259 path subvol_snapshots/1754/snapshot
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ID 4460 gen 15611 top level 259 path subvol_snapshots/1755/snapshot
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ID 4461 gen 15612 top level 259 path subvol_snapshots/1756/snapshot
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ID 4462 gen 15620 top level 259 path subvol_snapshots/1757/snapshot
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ID 4463 gen 15639 top level 259 path subvol_snapshots/1758/snapshot
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ID 4464 gen 15643 top level 259 path subvol_snapshots/1759/snapshot
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ID 4465 gen 15646 top level 259 path subvol_snapshots/1760/snapshot
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ID 4466 gen 15649 top level 259 path subvol_snapshots/1761/snapshot
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```
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`python subvolume.py /path/to/btrfs 259`:
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`subvolume_newway.py -r 258 /path/to/btrfs/ 259`:
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```
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Unique File Extents Extents added ontop Extents added ontop
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per subvolume of older subvolume of current(act) subvolume
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-------------------|-------------------|----------------------
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SubvolumId Size SubvolumId Size SubvolumId Size
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258 0.0B 258 0.0B 258 1.6TiB
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4186 0.0B 4186 0.0B 4186 0.0B
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4185 0.0B 4185 0.0B 4185 0.0B
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4184 0.0B 4184 0.0B 4184 0.0B
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4183 0.0B 4183 0.0B 4183 0.0B
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4182 0.0B 4182 0.0B 4182 0.0B
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4181 0.0B 4181 0.0B 4181 0.0B
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4179 0.0B 4179 0.0B 4179 0.0B
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4178 0.0B 4178 3.3MiB 4178 0.0B
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4177 0.0B 4177 0.0B 4177 188.0KiB
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4176 0.0B 4176 0.0B 4176 188.0KiB
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4175 0.0B 4175 0.0B 4175 188.0KiB
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4166 0.0B 4166 590.9MiB 4166 188.0KiB
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4130 8.0KiB 4130 6.1GiB 4130 164.0KiB
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4091 4.0KiB 4091 34.0MiB 4091 2.9MiB
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4072 0.0B 4072 4.8MiB 4072 3.0MiB
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4046 12.0KiB 4046 3.8MiB 4046 3.1MiB
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4040 8.4MiB 4040 11.0GiB 4040 11.6MiB
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3974 20.0KiB 3974 2.1MiB 3974 4.7MiB
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3942 128.0KiB 3942 3.9GiB 3942 4.8MiB
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3923 0.0B 3923 96.5MiB 3923 11.3MiB
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3913 0.0B 3913 556.4MiB 3913 11.3MiB
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3900 0.0B 3900 36.3MiB 3900 4.6MiB
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3887 0.0B 3887 995.6MiB 3887 4.6MiB
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3864 0.0B 3864 61.9MiB 3864 4.6MiB
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3857 0.0B 3857 3.1GiB 3857 4.6MiB
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3818 32.0KiB 3818 7.3GiB 3818 4.6MiB
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3764 116.0KiB 3764 7.9GiB 3764 4.9MiB
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3661 216.0KiB 3661 13.6GiB 3661 5.1MiB
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2694 8.0KiB 2694 590.7MiB 2694 4.8MiB
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2577 2.4MiB 2577 39.9GiB 2577 7.3MiB
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2395 1.7MiB 2395 54.2GiB 2395 53.5MiB
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2133 447.7MiB 2133 28.3GiB 2133 2.4GiB
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1949 151.0MiB 1949 1.4TiB 1949 2.1GiB
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Unique File Extents Extents added ontop Extents added ontop of
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per subvolume of previous subvolume current(act) subvolume
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---------------------|---------------------|----------------------
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SubvolumId Size Size Size
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258 0.00B 0.00B 1.46TiB
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4466 0.00B 0.00B 0.00B
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4465 0.00B 0.00B 0.00B
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4464 0.00B 0.00B 0.00B
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4463 0.00B 2.58MiB 0.00B
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4462 0.00B 0.00B 648.00KiB
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4461 0.00B 0.00B 648.00KiB
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4460 0.00B 1.18MiB 648.00KiB
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4459 0.00B 0.00B 996.00KiB
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4458 0.00B 0.00B 996.00KiB
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4457 0.00B 0.00B 996.00KiB
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4456 0.00B 0.00B 996.00KiB
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4455 0.00B 0.00B 996.00KiB
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4454 0.00B 0.00B 996.00KiB
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4452 0.00B 0.00B 996.00KiB
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4451 0.00B 0.00B 996.00KiB
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4444 0.00B 1.23MiB 996.00KiB
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4414 120.00KiB 12.38MiB 1.07MiB
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4392 184.00KiB 6.20GiB 1.19MiB
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4372 164.00KiB 3.64MiB 4.41MiB
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4337 176.00KiB 6.47MiB 4.48MiB
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4258 0.00B 1010.53MiB 4.91MiB
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4211 0.00B 1.97GiB 4.91MiB
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4196 36.00KiB 36.00KiB 5.64MiB
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4182 36.00KiB 3.66MiB 5.64MiB
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4166 140.00KiB 590.95MiB 5.80MiB
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4130 192.00KiB 6.04GiB 5.83MiB
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4091 1.75MiB 34.36MiB 7.49MiB
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4072 296.00KiB 9.12MiB 8.09MiB
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4040 8.96MiB 11.01GiB 16.72MiB
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3942 2.31MiB 4.16GiB 8.67MiB
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3887 1.59MiB 4.15GiB 27.33MiB
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3818 1.22MiB 15.20GiB 27.41MiB
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3661 2.43MiB 13.61GiB 27.43MiB
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2694 3.19MiB 40.44GiB 27.42MiB
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2395 6.55MiB 13.25GiB 62.80MiB
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2133 5.99MiB 17.44GiB 119.27MiB
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1949 42.48MiB 1.33TiB 166.50MiB
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Size/Cost of snapshots: 77.78MiB Volatility: 0.01%
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```
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Snapshot 2133 introduced 28GiB, where most of them still reside on the system (used by newer snapshot, 2395)
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Thus, deleting snapshot 2133, will only free 447MiB. Snapshot 2133 has 2.4GiB changed compared to current (258) subvolume.
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Snapshot 2133 introduced 17GiB, where most of them still reside on the system (used by newer snapshot, 2395)
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Thus, deleting snapshot 2133, will only free 6MiB. Snapshot 2133 has 119MiB changed compared to current/ active (258) subvolume.
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## Possible expansions:
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Calculate the size of metadata block differences.
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Take into consideration inline file extents.
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Does balance operation change the differences between snapshots?
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Why do we recieve the same extent with the same range many times?

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