View ZFS deduplication ratio on a dataset

deduplicationzfs

I have a tank consisting of several datasets, only one of which is configured to use deduplication.

How can I see the ratio for this dataset? I get a ratio of 1.00x for the whole pool but I imagine this is just reporting the ratio on what's in the tank, which is nothing (I only have datasets in the tank).

Best Answer

What you're referring to as a tank is really a ZFS pool and your datasets are ZFS filesystems within the pool.

ZFS deduplication has pool-wide scope and you can't see the dedup ratio for individual filesystems.

If you turn dedup on for a pool that already contains data, the existing data will not be automatically deduped and your ratio will still be 1.00x. Only newly written data will be deduped and then you may see the ratio increase.

Not splitting at spaces

bash's for loop splits the argument at all whitespace characters by default. You could somehow escape each line - or simply switch to another delimiter character. cut will return one value per line, so there's a newline in between which we can choose.

Watch out for the double quotes in zfs get all, so each $dataset doesn't get split up, too.

#!/bin/bash
IFS=$'\n'
for dataset in `zfs list -H | cut -f 1`
do
  zfs get all "$dataset"
done

Resetting IFS

Afterwards, you might want to reset IFS to the value before, store it to some temporary variable.

OLD_IFS=$IFS
# the whitespaces-sensitive lines
IFS=$OLD_IFS

Ubuntu – My ZFS dataset is gone after system upgrade/reboot (ubuntu)

I had the same Problem. Doing

apt-get install ubuntu-zfs zfsutils

and rebooting solved it for me. For some Reasons ubuntu did not update all zfs-packages. You can see if this is the case at the end of apt-get update output (packages held back)

Best Answer

Related Solutions

Shell Script – Handling Whitespaces in ZFS Dataset Names

Not splitting at spaces

Resetting IFS

Ubuntu – My ZFS dataset is gone after system upgrade/reboot (ubuntu)

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