

A Time Machine time bomb - lisper
http://rondam.blogspot.com/2009/09/time-machine-time-bomb.html

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pilif
how could that guy hook up an eSATA drive to his mac? As far as I can see,
none of the currently available machines provide eSATA support.

I thus assume that he was using OSX on a custom-built machine and it's very
well possible that OSX doesn't have built-in eSATA support (due to the lack of
official hardware) and thus doesn't recognize the external drives as external
ones.

You see, when I plug a USB or Firewire drive into my Mac, Time Machine doesn't
try to back them up.

~~~
pmjordan
Presumably using either an ExpressCard (in a MacBook Pro) or PCIe (Mac Pro)
eSATA controller. Not exactly what I'd call "custom built". Interesting
though, that it recognises USB and Firewire as external, but not eSATA. I
wonder if it supports hotplugging/ejecting of eSATA drives at all?

~~~
lisper
I use an ExpressCard. It didn't even occur to me that a drive connected this
way might appear to the OS to be an internal drive, but that actually makes a
certain amount of sense.

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bcl
When the backup drive get full Time Machine is going to delete the oldest
backups, that's how it works. Using it for a permanent backup solution isn't
too smart.

On my systems I also backup to a BackupPC system for longer term storage.

~~~
ajg1977
Exactly. Time machine is for those "oh shit, my disk is toast/I really didn't
mean to delete those files/I'm switching to a new mac" moments.

It's not intended to be used to retain a complete history of your machine and
as such if used for this purpose you're eventually going to get a nasty
surprise.

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avitous
On my Time Machine preferences pane it says 'Notify after old backups are
deleted'. I read this to imply if TM decided it needed a monstrous amount of
extra storage and decided it needed to delete a _lot_ (or all) of the old
backups, there wouldn't be any notification until they were gone. I don't see
any option to notify _before_ deleting them; perhaps a confirm option there
would have been useful?

~~~
lisper
That's how it was in Leopard. It changed in SL.

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chancho
I'm becoming less and less comfortable with hard drives as long-term backup
media. The other day I plugged in my external to back up some family photos,
but the drive wasn't coming up and while I was investigating (this was Linux
so it could have been any number of reasons) this faint noise was bugging the
crap out of me. "What is that, a metronome?" It took a few minutes before the
"oh shit" set in.

Time machine is nice because its nearly impossible to remember to do backups
regularly (unless it's your job) and the backups are highly available, but
really its more like an extended trash bin, not an archive. Storing your
backups on-site is one thing, but keeping them plugged in and mounted is just
asking for it.

Whatever happened to tapes? They're like comically expensive now. Another
option is to copy your Time Machine out to S3 once a month. (Would probably
take that long) but I don't know how you'd preserve the aliases / hard links.

~~~
tsally
Just have two external hard drives. I have one at home I use daily, and then
one I keep in my desk drawer at work I use weekly [1]. The chances of both
failing at once are pretty unlikely. You _could_ do the cloud, but I'm not
comfortable having all my data in the could. If you _have_ to use an external
provider, use Rysnc [2] . They seem trustworthy [3].

[1] <http://jwz.livejournal.com/801607.html>

[2] <http://rsync.net/>

[3] <http://news.ycombinator.com/item?id=702247>

~~~
MicahWedemeyer
Does it have to be "the cloud" as in S3? What about good old space on a
traditional host? I have a Dreamhost account that claims to offer "unlimited"
space for a flat monthly rate, and they support traditional *nix
rsync/scp/etc. Seems like a good fit to me.

~~~
duskwuff
Unlimited space for _web content_. Backups don't count as web content, and
will get you smacked down hard.

~~~
MicahWedemeyer
Very good to know :)

------
duskwuff
>> Newly mounted external drives should be excluded from backup by default.

Hey! Let's solve a backup trimming problem by _potentially never backing data
up_ unless the user digs around in their preferences! This seems like a cure
that's worse than the disease.

~~~
lisper
I wouldn't call irretrievably wiping out _all_ the backups of my primary hard
drive in order to make room to back up a media drive that I just mounted a
"backup trimming problem."

And by the way, I had that volume on my exclude list, but TM forgot about it.
(That's a problem that has been around since TM first appeared.)

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JimmyL
>> almost bordering on _legally actionable negligence_

Good luck with that, and please do call us when every single kernel
contributor gets sued because someone accidentally overwrites their Windows
partition when installing Ubuntu.

~~~
tsally
Linux disclaims all liability in the license. Seems like Apple might be bound
by a few more laws because they are actually selling a product.

~~~
JimmyL
Check the OSX license, available at
<http://store.apple.com/Catalog/US/Images/MacOSX.htm>. Excerpted:

YOU EXPRESSLY ACKNOWLEDGE AND AGREE THAT USE OF THE APPLE SOFTWARE IS AT YOUR
SOLE RISK AND THAT THE ENTIRE RISK AS TO SATISFACTORY QUALITY, PERFORMANCE,
ACCURACY AND EFFORT IS WITH YOU.

and

TO THE EXTENT NOT PROHIBITED BY LAW, IN NO EVENT SHALL APPLE BE LIABLE
FOR...LOSS OF DATA.

and for good measure,

THE APPLE SOFTWARE IS NOT INTENDED FOR USE IN THE OPERATION OF NUCLEAR
FACILITIES, AIRCRAFT NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL
SYSTEMS, LIFE SUPPORT MACHINES OR OTHER EQUIPMENT IN WHICH THE FAILURE OF THE
APPLE SOFTWARE COULD LEAD TO DEATH, PERSONAL INJURY, OR SEVERE PHYSICAL OR
ENVIRONMENTAL DAMAGE.

Bottom line is that these licenses don't mean much anyway - they just make it
slightly harder to sue someone, in the same way that those personal liability
forms you sign before doing anything are just to scare you. In the absence of
an explicit contract - as in Apple guarantees "this will not cause any data to
be deleted" - they've got a very good case that while it's sad you lost your
data, it's not their fault.

Paying for something may create more of an expectation, but does not (in and
of itself) guarantee you anything or increase liability.

~~~
tsally
Obligatory: IANAL

I knew that these disclaimers were in both licenses. However I think that the
fact that Linux is given away for free and that OS X is a product makes a
difference in the clause _TO THE EXTENT NOT PROHIBITED BY LAW_. I mean, you
can't buy an Apple computer without OS X on it. Are they really allowed to
disclaim all liability for everything? In my legally uneducated mind that
seems unlikely.

~~~
lisper
In most jurisdictions, whenever you accept money for a product there are
implied warranties of merchantability and fitness for a particular purpose.
Since TM is widely touted by Apple as one of the features of OS X they cannot
disclaim the warranty that it does what it is supposed to do, namely, back up
your data. What Apple has done is analogous to selling a fire extinguisher
that actually sets your house on fire. You can't disclaim liability for
something like that.

~~~
demallien
Apple have always sold TM as a way of doing backups not archiving. The
original article seems to want to have used TM as an archive, not a backup,
and that's where the problems came in.

That said, maybe I've missed something in the marketing that Apple have done
for the product - your comment seems to indicate that. Do you have any
specific examples of false claims made in marketing TM by Apple?

~~~
rwolf
TM would have deleted every backup they had if they didn't stop it in time.
Wanting every backup you've ever made is one thing; wanting the last backup
you made to be available doesn't sound like archiving.

~~~
dchest
No, it wouldn't. If it doesn't have enough space to keep at least one backup,
it won't delete previous backup, it will tell you that you need more space.

~~~
lisper
Happily, the logs record exactly what happened. The request was for 877.54 GB.
The TM volume is 731.95 GB. It deleted 14 old monthly backups (so just over a
year's worth) before I stopped it. But given that it had requested more space
than was actually available there is no reason to believe it would have
stopped before wiping them all, and in particular, before wiping all my
Leopard backups, which would have made it impossible for me to revert.

~~~
dchest
It didn't delete the latest backup on my drive. It told me that there's not
enough space, but backup is still there.

------
martey
It is not clear from the article whether this happened because the author
upgraded to Snow Leopard, or because they switched their external hard drive
to eSATA. If the former, the behavior might be caused by the fact that Snow
Leopard is a new operating system, and many of the system files that were in
OS 10.5 have changed.

Have any readers that have upgraded to OS X 10.6 experienced the same issue?

~~~
lisper
It's both. I upgraded to Snow Leopard, _and_ I remounted external drives. In
Leopard, there was an option to warn before deleting old backups. In SL that
option has changed to "notify after deleting old backups." That plus deleting
the external volumes from the exclude list was the nasty combination.

~~~
lurch_mojoff
You also say that you switched from USB to eSATA. There is a very good chance
that from the perspective of the OS these are entirely new dives, maybe even
seen as internal drives. There may not be an issue in the Time Machine code,
but rather this whole thing is unfortunate edge case of intended behavior.

~~~
lisper
Yes, I think that might be right. That hadn't occurred to me before.

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desu
This behaviour sounds perfectly reasonable for the common case, for whom it
was designed.

Furthermore it sounds like this guy is using Time Machine as an archiving
solution, not a backup solution. You shouldn't be all that worried to lose
backups a year old if you know newer ones are intact. You should never delete
a document there's any chance of ever needing again, then rely on TM or
similar to save it for you.

~~~
lisper
I'm not worried about losing the old backups. But I would be worried about
losing _all_ of my backups, which is what _would_ have happened if I had not
noticed what was happening and stopped it manually.

