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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