How The Backup Process Has Changed [LWN.net]

How The Backup Process Has Changed

Posted Nov 29, 2007 19:31 UTC (Thu) by jimparis (subscriber, #38647)
In reply to: How The Backup Process Has Changed by nix
Parent article: How The Backup Process Has Changed

OK, so copy static LVM binaries and configuration to a temporary ramdisk and run them from
there.  There's nothing special about "the root filesystem", there's just something special
about "the filesystem that lvm lives on".

And don't snapshot an active swap, that could get ugly :)

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How The Backup Process Has Changed

Posted Nov 30, 2007 1:33 UTC (Fri) by nix (subscriber, #2304) [Link]

You might need to modify it to write its config backups and things 
somewhere else (preferably make it configurable at runtime).

But yes, if you can avoid those problems then that might work, and thanks 
to tmpfs pretty much everyone has the moral equivalent of a ramdisk within 
easy reach.

(Snapshotting an active swap partition is just barmy. Snapshotting a 
filesystem containing an active swapfile is careless and risky, but 
thankfully swapfiles tend to get used only for short-term 
oh-shit-we-need-another-X-Gb-of-swap-right-now stuff, at least in my 
experience. They're not something you habitually run with for ages.)

How The Backup Process Has Changed

Posted Nov 30, 2007 4:56 UTC (Fri) by njs (subscriber, #40338) [Link]

>thankfully swapfiles tend to get used only for short-term
oh-shit-we-need-another-X-Gb-of-swap-right-now stuff, at least in my experience. They're not
something you habitually run with for ages.

Wandering *way* off topic, is there actually any reason we don't all use swap files these
days, other than inertia?  They certainly allow more flexible on-the-fly configuration of your
swap needs, and I'm not aware of any disadvantages.  Seems like a desktop distro optimizing
for simplest-thing-that-works would be quite sane to just slap a single partition on the hard
disk and then allocate a swapfile in it.

How The Backup Process Has Changed

Posted Nov 30, 2007 8:22 UTC (Fri) by nix (subscriber, #2304) [Link]

I'd go with inertia too.

Splitting up your fs into more than one big lump still has advantages 
(putting your data somewhere else allows you to blow away the rest more 
easily: you can hive off filesystems as a whole onto remote storage 
slightly more easily: it keeps them safe from each other being corrupted 
to some degree; you can mount them readonly and so on) but IIRC the only 
advantage of swap partitions these days is that they're guaranteed to be 
contiguous.