[Duplicity-talk] Predicting size of ~/.config/duplicity/

[William Furnass]

Hi,

I'm wanting to use LVM2 to create snapshots of my home and root
partitions then back up those using duplicity to ensure that I get
point-in-time backups. The issue I have at present is knowing how
much space to allocate to my root snapshot, which is typically a
function of how much churn there is under /root/.config/duplicity.

Is there a calculation that gives me a worst case estimate for how
much might be changed/written in .config/duplicity over the course of
a backup, using e.g. the total number of files in non-excluded
directories?

Cheers,

Will

[Kenneth Loafman]

Interesting question. I don't have a real answer for the general case, but
basic assumptions may give you an idea:

1. compression and encryption only affect the target file size
2. manifest files take up about 300 bytes per volume plus the file list
3. sigtar files take 4 bytes per block depending on file size
1. under 10k the block size is 512
2. over 10k the block size is given by
file_blocksize = int((file_len / (2000 * 512)) * 512)
return min(file_blocksize, globals.max_blocksize)

So, as you can see, the size is dependent on too many variables that change
with each user's situation.

...Ken

interesting question. any idea? ..ede
-------- Forwarded Message --------
Subject: [Duplicity-talk] Predicting size of ~/.config/duplicity/
Date: Wed, 30 Mar 2016 10:29:00 +0100
Hi,
I'm wanting to use LVM2 to create snapshots of my home and root
partitions then back up those using duplicity to ensure that I get
point-in-time backups. The issue I have at present is knowing how
much space to allocate to my root snapshot, which is typically a
function of how much churn there is under /root/.config/duplicity.
Is there a calculation that gives me a worst case estimate for how
much might be changed/written in .config/duplicity over the course of
a backup, using e.g. the total number of files in non-excluded
directories?
Cheers,
Will
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