Anno domini 2024 Sat, 28 Sep 21:23:36 +0000
dep via tde-users scripsit:
said Dan Youngquist via tde-users:
| On 9/28/24 9:18 AM, Dr. Nikolaus Klepp via tde-users wrote:
| > I intend to oject: filesystem based backup systems do not have the
| > risk of saving a corrupt filesystems as blockbased backup systems have
| > when done on a mountd filesystem. The filesystem (as long as it is
| > sane) is always in a cosistent state, while the blockdevice (as long
| > as mounted) is not. That's why no sane person uses dump/restore
| > anymore.
| >
| > As long as you do not run "apt dist-upgrade" at the same time as you
| > rsync you are fine (in respect of bootable backup). Nothing changes
| > kernel + grub + modules + /bin ... under normal conditions so your
| > copy will be able to boot - that is if your got UUID and GRUB/EFI
| > stuff right in the first place. What gets busted are logfiles, open
| > datanbases, files that are just been written. So if you use some brain
| > cells you can shut down whatever is not essential, close your kmail +
| > editors + firefox and just make the sync. Snapshots (ZFS) would be
| > better, but you take what you get :)
So, basically, it would be simply to do nothing while the sync is made,
yes? Is this a fairly quick function or a long, complicated one?
I've actually had that question about the copy function in, for instance,
Konqueror, for decades. If I'm copying a directory that contains
different-sized files with the same name, will it pick up more than the
filename when asking if I want to overwrite? Would be nice to see a
comparison and possibility of rename. (Not in this particular case, but it
would be a big help in, say, backing up my 8tb of pictures. I'd like to be
able to use autoskip, but not at the cost of losing edits.)
| You're probably right; I've never backed up a running boot partition
| with rsync. But if I were going to depend on it, I'd want to test it a
| time or two first.
What is regularly written in / besides log files?
Depends on what's mounted under / - usually only logfiles that are of less interest
when restoring.
| Is it really necessary to backup after every single
change? Should you
| ever need to use the backup, updates and other software can always be
| quickly & easily reinstalled. User configuration settings will still be
| in /home, since it's on a separate partition. So maybe a few backups a
| year would be sufficient.
For that matter, I could just boot into the other drive and do the
update/upgrade thing. Which would cover a lot but probably not everything.
I was hoping to avoid this, but it looks increasingly as if that's what it
will have to be.
But you'd need a copy of the EFI boot partition on both drives, with different UUID,
but same content in sync.
| > A RAID 1 seemed a good idea, but I believe that
this cannot be added
| > to a drive after the fact -- both must be blank to start with. And I
| > think the speed would then be determined, at least to some extent, by
| > the slower drive.
|
| I know very little about RAID, but would it be possible to backup the
| existing drive, make the RAID 1, then restore the backup to it? Or
| would that not work for some reason?
Someone more skilled than I am could probably do it. But I'm not utterly
familiar with the new bios-related stuff beyond having learned it is
deceptively easy now to make a drive unbootable. I do not know what
establishing the software RAID would write that restoring from backup
might overwrite.
RAID volumes: filesystem lives on top of it, so it's not affected. But RAID oly
checksums writes, not reads, so when your drive silently zeroes blocks on reading it's
no use. ZFS: magic and just works.
| re: speed, is it possible to make the RAID default
to the faster drive,
| then update the slower drive in the background? Or maybe it does that
| anyway?
There must be some mechanism for this, because otherwise a main reson for a
RAID would be removed.
Speed is not the intention of RAID. Resilvering is done in the background - that's the
task where most drives fails, so keep an eye on the log.
Nik
There is no doubt out there an application that does
what I'm looking for,
though I thought there was no doubt an application that would ping oevery
x seconds and log the results. If there was one, I didn't find it.
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