Re: [gentoo-user] [OT] SMR drives (WAS: cryptsetup close and device in use when it is not)

[William Kenworthy]

On 2/8/21 5:38 am, Frank Steinmetzger wrote:
> Am Sun, Aug 01, 2021 at 11:46:02AM +0800 schrieb William Kenworthy:
>
>>>> And you are storing several machines into a single repo? The docs say this
>>>> is not supported officially. But I have one repo each for /, /home and data
>>>> for both my PC and laptop. Using a wrapper script, I create snapshots that
>>>> are named $HOSTNAME_$DATE in each repo.
>>> Basicly yes: I use a once per hour snapshot of approximately 500Gib of
>>> data on moosefs, plus borgbackups 3 times a day to individual repos on
>>> moosefs for each host.  3 times a day, the latest snapshot is stuffed
>>> into a borg repo on moosefs and the old  snapshots are deleted.  I
>>> currently manually push all the repos into a borg repo on the USB3 SMR
>>> drive once a day or so.
>>>
>>> 1. rsync (and cp etc.) are dismally slow on SMR - use where you have to,
>>> avoid otherwise.
>>>
>>> forgot to mention
>> 1a. borgbackup repos are not easily copy'able - each repo has a unique
>> ID and copy'ing via rsync creates a duplicate, not a new repo with a new
>> cache and metadata which depending on how you use can cause
>> corruption/data loss.  Google it.
> Yup. Today I did my (not so) weekly backup and rsynced the repo to the new
> drive. After that I wanted to compare performance of my old 3 TB drive and
> the new SMR one by deleting a snapshot from the repo on each drive. But Borg
> objected on the second deletion, because “the cache was newer”. But that’s
> okay. I actually like this, as this will prevent me from chaning two repos
> in parallel which would make them incompatible.
>
Keep in  mind that both repos have the same ID - you should also rsync
the cache and security directories as well as they are now out of sync
(hence the warning).  Be very careful on how you do this - you are one
step away from losing the while repo if the cache gets out of sync.  The
docs warn against rsyncing two repos and then using them at the same
time for a good reason.

BillK