Mac OS X backups

[grumpy_sysadmin]

While Time Machine has been much-ballyhooed, it is not exactly a backup product (it provides continuous data protection-provided you keep the extra hard drive that you MUST use for Time Machine to work at all connected at all times), nor is it a host imaging product. It's good for "damn, I didn't mean to change that file that way", but it's not

Comments

[grumpy_sysadmin]

Looks like bless(8) is overkill if you're rsyncing a known-bootable drive.

I think Brad was doing that because he was shoe-horning a bunch of files from install media onto a USB stick and mangling the owners (regardless of whether he had the volume set to respect them, the files got their with the wrong ones) by just doing file copies in the process.

[grumpy_sysadmin]

s,got their,got there,

[jwz]

I suspect that vsdbutil does the same thing as: 1) mount drive; 2) get info; 3) uncheck "ignore ownership". But you like making things hard.

Holding down the "menu" button on the IR remote while booting does the same thing as holding down "Opt". Handy if, like me, you can't remember which key on your keyboard the Mac thinks is "Opt" in its pre-remapped state.

By the way, physically swapping a drive in an Intel iMac is a 3 hour job. I've done it. You have to take the screen out, which involves peeling up conductive tape all over. It's insane.

[grumpy_sysadmin]

I agree that's what vsdbutil does. I didn't use it because I like making things hard (I don't, in a global sense), but... First, because of a prior conversation with pdx6 in which he'd used your method (prior to the update), fired, forgot, and later found the drive unbootable. So I went looking for how to make it bootable, and I'm still not sure I quite understand what Apple actually means by "owners" here. Second, I'm still doing it, because re-asserting the setting doesn't break anything and I don't want to have to remember to go pointy-clicky things if I switch out the target drive later (or reformat it temporarily for something else, which I know I'll do shortly). I do probably make things harder than absolutely necessary to rule out corner cases I'll never actually encounter, but I prefer reducing the risk

[jwz]

I don't do much remapping -- just swap Alt and Cmd, and make Caps be Control. But since it's not an Apple keyboard, I never remember whether Alt is the one with a sideways-man on it or the one with a fish.

I'm pretty sure that all "ignore owners" does is make all file owners/groups be seen as the user who mounted the file system. Kinda like nfs root_squash, but for everybody.

[grumpy_sysadmin]

Right, right, and you still use the non-rectangular style of keyboard for the wrists, so Apple keyboards are pretty useless for you. I remember now.

I also figure "ignore owners" does what you said first (but I don't think it means quite the same thing as root_squash, exactly), but again... undocumented crap. I guess there's a prayer this one might actually be visible in the Darwin source, but I certainly don't have the patience to go look.

[stepleton]

"+1 Informative," he said, provoking a comment about how long it's been since grumpy_sysadmin has visited Slashdot.

[grumpy_sysadmin]

Yeah, I definitely ceased to find anything worth paying attention to in slashdot roughly five years ago.

[ultranurd]

I use Carbon Copy Cloner, which basically just sits on top of rsync and bless, and invokes them with launchd.

[grumpy_sysadmin]

That doesn't sound like something I can run out of cron on the FreeBSD box with the Disk feeding scripts to clients that they should execute to perform their network backups.

[grumpy_sysadmin]

I may have dismissed that with less detail than would be necessary to be clear: I recognize that there's a lot of fancy GUI crap in Mac OS X. I'm glad it's there when I want to watch a movie or look at a web page. I really have no use for it for things like backup. I'm glad that works for you, but I'd rather do my own sitting atop of rsync(1) and bless(8).

[ultranurd]

What can I say, I really, really like progress bars.

[cjensen]

There this Mac disk cloner thing SuperDuper which seems to make a bootable clone and is free for doing just that. Would it suffice to make the bootable clone, and then rsync after that?

Or do I really need to keep begging OSX to preserve userids before every rsync and blessing after every rsync?

[grumpy_sysadmin]

I think I've read about SuperDuper. It's not clear to me that it has all that much utility beyond what Apple provides (you can do those same things with Disk Utility.app and hdiutil(1), for the most part, never mind some Apple-provided CLI thing that's somewhere between pax(1) and rsync(1)--lacking the massive transfer time speedup of rsync(1)). If you would prefer to pointy-clicky things, go for it, but I've never used it so maybe it does something wrong: I just don't know.

I'm 100% certain I know what rsync(1) does because, back during college when I had time to blow on this kind of sidetrack, I actually looked through the source to understand how it was doing things and why it was doing them that way, since I was impressed by its cleverness. I still am. The commercial backup market is just now catching up on this, though it's taking it a step further with certain deduplication products. I have this fantasy in which I have the free time to tack rsync's algorithm into Bacula. Alas, I don't have that kind of free time at the moment,

[cjensen]

SuperDuper's great when rsync fails with an out of memory error on your four-year-old 12" Powerbook that needs a RAM upgrade before you can install Leopard anyhow, and you don't feel like troubleshooting that at 9 on Friday because Netflix *can* deliver the right DVD in the right envelope, at least to my house.

--SJ