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Why I Don’t Rely on Time Machine

joeontech.net

11–20 of 43 posts

Re: Why I Don’t Rely on Time Machine

#11
Surely it's OK for a backup drive to fail occasionally. Your working drive might fail occasionally too but it's extremely unlikely that both of them fail within a day or so of each other. That's the situation that would lead to loss of data.

That's for a pure backup. For a history of previous versions, of course you'd want more reliability if you only have one copy of that history.

Re: Why I Don’t Rely on Time Machine

#12

Surely it's OK for a backup drive to fail occasionally. Your working drive might fail occasionally too but it's extremely unlikely that both of them fail within a day or so of each other. That's the situation that would lead to loss of data. That's for a pure backup. For a history of previous versions, of course you'd want more reliability if you only have one copy of that history.

I think the concern here is that the backup drive could have silently failed at some point in the past, corrupting the backups, and then the primary would fail too, leaving you without any backups whatsoever.

Re: Why I Don’t Rely on Time Machine

#13

Surely it's OK for a backup drive to fail occasionally. Your working drive might fail occasionally too but it's extremely unlikely that both of them fail within a day or so of each other. That's the situation that would lead to loss of data. That's for a pure backup. For a history of previous versions, of course you'd want more reliability if you only have one copy of that history.

When you only have a master and backup drive, in the case of failure, you put yourself in a critically dangerous position.

Restoring from backup isn't just stressful for the human, it's also stressful for the hardware.

When you have a single failure, it's nice to at least have TWO independent backups in case during the restore there is a second failure (either due to hardware or operator).

Re: Why I Don’t Rely on Time Machine

#14

I'm convinced that time machine over a network is a bad idea. Seems convenient, but if there's network flakiness, TM will decide that the backup is bad and force you to create a new one. And the first step in that process is to delete the existing backup. I had that happen once, when the drive I was backing up was in the process of failing. It got about 5gb into the new backup before it was totally dead. Even a somew…

Deleting the old backup is no longer the first step AFAIK. Yes, I have seen that behaviour in the past. Now, it gets renamed and then deleted once the next backup is completed successfully.

Re: Why I Don’t Rely on Time Machine

#15
my solution is an external WD drive that has RAID1. It's not gonna save me from all scenarios of failure, but it does increase my confidence that if my computer dies, i'll be able to get data back. I also rotate out drives and keep them for historical purposes to have something to go back to that might be several months old, but at least have my "stuff".

Re: Why I Don’t Rely on Time Machine

#16
I use Time Machine for full system backups, mainly for convenience if my SSD fails. I also rsync onto two separate drives the two main folders that I'd be devestated to lose: photos and music.

I also always liked the quote of there only being two HDD's in the world: ones that have failed and ones that haven't failed yet.

Re: Why I Don’t Rely on Time Machine

#17
I had exactly that story, disk crashed, time machine not working. Fortunately most of the data on the disk was ok and I had cloud backup as a second backup. For me Time Machine + Arq for online backup makes me feel safe...

Re: Why I Don’t Rely on Time Machine

#18
I've never used Time Machine specifically because I heard early reports of it not saving someone who suffered a total disk failure. I haven't bothered trying it since then. (First impressions are powerful things.)

I've used Carbon Copy Cloner (a glorified rsync + a great UI) for 5+ years and I've survived no less than two total disk failures. The best part is that CCC makes my full-disk backups bootable, so I can literally plug in my USB drive (or my 256GB SD Card--yes, I do full-disk backups to SD cards) and boot my entire laptop directly from the external drive, bypassing my (possibly defunct) internal disk. That allows me to continue working while I wait to get my laptop replaced.

When the new laptop arrives, I install CCC and do the imaging in reverse, copying the external disk to my new Mac. Then I reboot and my laptop is back to the way it was the last time I used it. (This depends on replacing my old laptop with a new one using the same hardware, but that's not difficult if I stay within a few years of the latest hardware.)

Re: Why I Don’t Rely on Time Machine

#19
I had a similar problem. I encrypt the backups. The container partition that holds the encrypted partition had a corruption. TM took forever to backup, and then failed. Deleting the encrypted partition didn't solve the problem. Although this is not related to TM, it had the same effect. I didn't try to restore from this backup, looking back that was a mistake, just to see if that still worked. I had to erase the disk, create a new container partition and a new encrypted partition, and now it works.

I use Crashplan as well, two external disks, one offsite, one of 4TB with three partitions, one for TM, two to sync a backup using Superduper - the paid version that just backs up the difference. I hope this is good enough.

Re: Why I Don’t Rely on Time Machine

#20
post #3

This is a good time to remind people about proper backups: the 3-2-1 rule. 3 backups. 2 backups (or more) should be on different mediums. 1 (at least) should be offsite (ie. home copy at work or in the cloud) You need three backups. If we assume that every copy has a chance small but real chance of failure, the chance of all failing at once becomes exponentially less with each copy. You need at least two different sy…

I like to say that if you have 1 copy, you have none. If 2, 1, if 3, you have 2 copies, the absolute minimum. And try to decrease single points of failure, e.g. I use rsync for rsync.net and BackupPC to local disk, and tar to LTO tape after giving up on the opaque and baroque Bacula.

You need one offsite to prevent your house burns down and takes your machines and local backups.

I'm a long term fan of tape, from the first time I used UNIX(TM) in 1978 and a DECTape saved me when I was learning the power of the -rf flags to rm.

LTO tape systems for the home are not insanely expensive (then again, this is my minimum system today: https://news.ycombinator.com/item?id=10483361 ECC is a requirement for me). Street price for the HP LTO-4 internal SAS EH919SB I'm currently using is ~1,300 USD (and it wasn't difficult to get it at around that price in 2011).

Add a LSI 2004 chip based SAS-2 controller such as the "Avago" LSI 9211-4i at $167 from Newegg right now to drive it, and a semi-disposable flash drive to feed it quickly so the tape doesn't "shoe shine" (the tape moves very quickly, if you don't feed it quickly enough it has to stop the tape and backup enough so that it's at speed when it starts forward again and hits the location where it ran out).

I.e. at whatever speed write a 10GiB slice of your backup to the flash drive, then write that all at once to the tape. Considering media costs, if you start from scratch today you'd probably be better off going LTO-5 now that LTO-6 is shipping, the media costs the same as for LTO-4 despite a near doubling of capacity. I've got enough LTO-4 tapes that I'll keep using them until my LTO-4 drive dies, then buy an LTO-5 drive, which per the standard can read two earlier generations, and write 1 earlier, and new LTO-5 media for it.

Current LTO-4 and LTO-5 tapes from HP or Fuji (I wouldn't trust anyone else) go for $22-23, uncompressed capacities are 800 and 1.5 GB respectively.

And then store copies off-site, and copy your most important stuff at least once a day to a site like rsync.net, which saved me when a tornado trashed my apartment in 2011.

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