significantly reduce cache space needs #235
Description
after converting an attic repo to borg (using #231), i am having problems running borg create. i suspect this is not related to the migration, but with the new caching algorithm that borg uses.
when running borg create, it seems to want to regenerate the chunks cache, even though it was converted and is available in $BORG_CACHE_DIR/<id>/chunks:
# borg create --do-not-cross-mountpoints --stats /media/anarcat/BOOK/borg::$(hostname)-$(date +%Y-%m-%d)-post-attic / /boot /usr /var /home --exclude-caches --exclude "/home/*/.cache" --exclude "*/.Trash-*" --exclude "*/[Cc]cache/*" --exclude "*/.bitcoin/blocks/*" --exclude "/tmp/*" --exclude "*/build-area/*" --exclude "/proc/*" --exclude "/dev/*" --exclude "/sys/*" --exclude "/var/cache/*" --exclude "/var/tmp/*" --exclude "/var/log/*" -v -v
Synchronizing chunks cache...
Archives: 284, w/ cached Idx: 9, w/ outdated Idx: 0, w/o cached Idx: 275.
Fetching and building archive index for marcos-2015-08-22 ...
Merging into master chunks index ...
Fetching and building archive index for marcos-2015-04-15 ...
Merging into master chunks index ...
Fetching and building archive index for marcos-2015-05-17 ...
Merging into master chunks index ...
[...]
Fetching and building archive index for marcos-2015-02-19 ...
hashindex: /root/.cache/borg/d31f0c3d6969eb44b6a77eb4edac2ec0c1d257c8fbb3a0e26ae4cede83963a89/chunks.archive.d/28fbf8d98f730e04b9835e2c628fed6f00f057267979ed9b3b7c1497782760ca.tmp: fwrite buckets failed (No space left on device)
... you can see how it's quickly running out of space. whereas the cache directory was 1GB in Attic, this ran out of space after 8GB written.