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#14269 - 02/18/11 10:50 PM Re: Opinon on time machine [Re: roger]
tacit Offline


Registered: 08/03/09
Loc: Portland, Oregon, USA
Originally Posted By: roger
since we're talking about what TM does, I hope that this is an acceptable place for this query.

if I run TM, then delete files from the computer, then run TM again, the deleted files still exist on the TM drive, correct? TM just creates a second, updated backup, leaving the first intact?


Yep!
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#14275 - 02/19/11 08:07 AM Re: Opinon on time machine [Re: tacit]
MicroMatTech3 Offline


Registered: 08/04/09
I am not able at the moment to find a definitive explanation of how Time Machine works, but it was my understanding that it is a backup utility, not an archiving utility. At some later time, the only copy in the Time Machine backups of the file that was deleted from the source volume after being backed up by Time Machine will exist only in what will have become a very old Time Machine backup. If that backup is deleted to create more free space, the file will be nowhere.

If a file still exists on the source volume, then it should be present in at least one of the Time Machine backups, but if it has been deleted from the source volume, it may not be in the Time Machine, depending on elapsed time and disk space use.

Please correct me if I have misunderstood how Time Machine works. Also, I do not understand why this text is frequently quoted but seems to have no original source on the Web:

(from http://en.wikipedia.org/wiki/Time_Machine_%28Mac_OS%29)

"Time Machine is a backup utility, not an archival utility, it is not intended as offline storage. Time Machine captures the most recent state of your data on your disk. As snapshots age, they are prioritized progressively lower compared to your more recent ones."[citation needed]
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#14276 - 02/19/11 08:44 AM Re: Opinon on time machine [Re: MicroMatTech3]
roger Offline


Registered: 08/04/09
Loc: Vermont
thanks, tacit and MMT3! I think what I might do is copy the files I want to keep, but don't need on the laptop, into a separate folder on the TM drive (there's plenty of room, it's 2Tb). then I'm assured that I have them, and wouldn't need to worry about the TM backup disappearing.
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#14279 - 02/19/11 10:08 AM Re: Opinon on time machine [Re: MicroMatTech3]
kevs Offline


Registered: 12/07/09
Micromat, thanks -- were you answering my final questions? I'm not sure clear?

Here are my finals again, (sorry for being redundant)


I assumed:

1) I could use an old 250 GB external, and then time machine would back up all files that are changed starting now.

no go? the documentation implied I need to first backup everything I own, meaning I have to buy another new 3TB external is this correct? bummer if so.

2) I would also assume I can include/exclude which folders get backed up, but I did not see this in the documentation. Not possible?

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#14280 - 02/19/11 11:36 AM Re: Opinon on time machine [Re: roger]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
Originally Posted By: roger
if I run TM, then delete files from the computer, then run TM again, the deleted files still exist on the TM drive, correct? TM just creates a second, updated backup, leaving the first intact?


It doesn't delete them immediately tho I'm not sure at what point it decides to delete them. There is an option to delete a file along with all time machine backups of the time, I don't recall offhand how you invoke it. (secure erase of trash?)
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#14281 - 02/19/11 11:50 AM Re: Opinon on time machine [Re: kevs]
jchuzi Online


Registered: 08/04/09
Loc: New York State
Quote:
I would also assume I can include/exclude which folders get backed up, but I did not see this in the documentation. Not possible?
Very possible. Go to System Preferences > Time Machine and click the Options button. You can exclude items from there.
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#14282 - 02/19/11 01:43 PM Re: Opinon on time machine [Re: roger]
joemikeb Online

Moderator

Registered: 08/04/09
Loc: Fort Worth, Texas
Originally Posted By: roger
if I run TM, then delete files from the computer, then run TM again, the deleted files still exist on the TM drive, correct? TM just creates a second, updated backup, leaving the first intact?

Correct and that file will remain in the TM backup until you run out of room on the TM drive and the backup it is contained in "fall off the backside" of the entire backup set.
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#14283 - 02/19/11 04:42 PM Re: Opinon on time machine [Re: joemikeb]
kevs Offline


Registered: 12/07/09
JON,
thanks, it looks like you can exclude only hardrives, (which is good), but not folders. correct? And will it just start filling up with whatever I now update or do I have to have a external hardrive with the space to match the 2TB of data I have on my main drive?

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#14284 - 02/19/11 07:15 PM Re: Opinon on time machine [Re: MicroMatTech3]
Hal Itosis Offline


Registered: 09/03/09
Loc: 10.6.8 (build 10K549)
Originally Posted By: MicroMatTech3
I am not able at the moment to find a definitive explanation of how Time Machine works, but it was my understanding that it is a backup utility, not an archiving utility.

As one ComputerWorld.com article said, Apple keeps most of those details close to the vest. [i'm pretty sure there's no developer or knowledge-base doc which describes TM's decision-making process to any deep extent, but it would be a pleasure to be proven wrong about that.]

Our fellow member ganbustein has written several posts on the matter, including:

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#14285 - 02/19/11 07:25 PM Re: Opinon on time machine [Re: kevs]
Hal Itosis Offline


Registered: 09/03/09
Loc: 10.6.8 (build 10K549)
Originally Posted By: kevs
it looks like you can exclude only hardrives, (which is good), but not folders. correct?

Folders can be individually excluded... but, they must reside on a disk which is already included.

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#14287 - 02/19/11 08:07 PM Re: Opinon on time machine [Re: Hal Itosis]
MicroMatTech3 Offline


Registered: 08/04/09
Hal,

Thanks for the details, especially the fact that the excluded folder must be on an included volume. MicroMat suggests that users of TechTool Pro exclude the backups of the disk directory made by the TechTool Protection feature, which are at /Library/Application Support/TechTool Protection/Volume_Name.

If I recall correctly, you had a list of the files that Apple automatically excludes from Time Machine. Ah, Yojimbo finds it, provided I can find one posting somewhere that mentions one distinctive excluded file:

(from the ancient forums)

Leopard tips? What's good?
10/28/07 08:50 AM

Hal Itosis
MacWizard

Reged: 08/23/99
Posts: 5114
Loc: 10.5.0 (build 9A581)


Files auto-excluded from Time Machine backups [re: Hal Itosis]
11/09/07 09:43 PM
Reply

Files auto-excluded from Time Machine backups...
code:

$ defaults read /System/Library/CoreServices/backupd.bundle/Contents/Resources/StdExclusions
{
ContentsExcluded = (
"/Volumes",
"/Network",
"/automount",
"/.vol",
"/tmp",
"/cores",
"/private/tmp",
"/private/Network",
"/private/tftpboot",
"/private/var/automount",
"/private/var/log",
"/private/var/folders",
"/private/var/log/apache2",
"/private/var/log/cups",
"/private/var/log/fax",
"/private/var/log/ppp",
"/private/var/log/sa",
"/private/var/log/samba",
"/private/var/log/uucp",
"/private/var/run",
"/private/var/spool",
"/private/var/tmp",
"/private/var/vm",
"/private/var/db/dhcpclient",
"/private/var/db/fseventsd",
"/Library/Caches",
"/Library/Logs",
"/System/Library/Caches",
"/System/Library/Extensions/Caches"
);
PathsExcluded = (
"/.Spotlight-V100",
"/.Trashes",
"/.fseventsd",
"/.hotfiles.btree",
"/Backups.backupdb",
"/Desktop DB",
"/Desktop DF",
"/Network/Servers",
"/Previous Systems",
"/Users/Shared/SC Info",
"/Users/Guest",
"/dev",
"/home",
"/net",
"/private/var/db/Spotlight",
"/private/var/db/Spotlight-V100"
);
UserPathsExcluded = (
"Library/Application Support/MobileSync",
"Library/Application Support/SyncServices",
"Library/Caches",
"Library/Logs",
"Library/Mail/Envelope Index",
"Library/Mail/AvailableFeeds",
"Library/Mirrors",
"Library/PubSub/Database",
"Library/PubSub/Downloads",
"Library/PubSub/Feeds",
"Library/Safari/Icons.db",
"Library/Safari/HistoryIndex.sk"
);
}


____

verified perms? • done fsck or safe boot? • cleaned caches & logs?
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Makers of TechTool

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#14288 - 02/19/11 09:13 PM Re: Opinon on time machine [Re: Hal Itosis]
ganbustein Offline


Registered: 08/04/09
Originally Posted By: Hal Itosis
[quote=MicroMatTech3]As one ComputerWorld.com article said, Apple keeps most of those details close to the vest.

Our fellow member ganbustein has written several posts on the matter, including:

First off, thank you very much for providing those links to my previous posts. You've spared me a lot of work.

But I'm not sure what details the ComputerWorld.com article thinks Apple is keeping close to the vest. The Time Machine preference pane (in System Preferences) provides, in 32 words, a very nice summary of how it works that is detailed enough for the vast majority of users. The "magic" that makes it all possible boils down to two features new to Leopard: the FSEvent mechanism that lets TM (or any application) rapidly discover where files have changed since an arbitrary time in the past, and the ability to make hard links to folders on an HFS+ volume, which TM uses to save backup space when nothing in a folder has changed. TM also makes use of extended attributes and ACLs, but that's only for fine-tuning. (It uses extended attributes to record when a file was first backed up and when it was replaced, so it can quickly jump to the prior or next version without having to scan intermediate backups looking for the inode number to change. It uses ACLs to make everything in the backup non-deleteable, so users won't be tempted to "tune" the backup behind TM's back by deleting or renaming individual files.)

All four of those features are independently documented in the developer documentation. How exactly TM puts them to use is of interest only to people like me who like to dig into how things work. The details are not complex, and are in any event easily discoverable. It's much less complex than even one PhotoShop image filter, but no one complains that Adobe "keeps the inner workings of 'Sharpen Image' close to the vest." What it (either Time Machine or Sharpen Image) does is apparent; how it does it is not important to anyone but the programmers.

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#14292 - 02/20/11 08:01 AM Re: Opinon on time machine [Re: ganbustein]
kevs Offline


Registered: 12/07/09
So guys, for this to work, my 500GB drive wont work?

I have to buy a new expensive 3TB drive to match the 3TB of data I have?

It just can't start on the cuff backing up data from my new 3TB external hard drive over to my backup 500GB?

I'm not sure I'm willing to buy a new 3tB drive just for time machine when I have an excellent 500GB drive I'm not using.

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#14293 - 02/20/11 09:03 AM Re: Opinon on time machine [Re: kevs]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
initially it need to make one full copy of anything not being excluded. So if you have a 3tb drive, with say 1tb of data on it, it can't even make the first initial backup on a 500gb drive.

If you truly want time machine to be an incremental backup the general rule of thumb I've heard is to have the backup drive be twice the capacity of the drive it backs up.

For a 3tb drive, I suppose you'd be looking at getting a drobo and stuffing it with 2tb drives?
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#14294 - 02/20/11 09:44 AM Re: Opinon on time machine [Re: Virtual1]
kevs Offline


Registered: 12/07/09
It looks like I wont be using time machine after all.
Pity it just cannot start off the cuff backing up stuff to any size drive.

Also curious how does it work? It need all this data on the TM back up disk. But aren't we backing up from the primary drives?
It "sees" what I did on a primary drive and then find the corresponding file and backs that up on TM?

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#14298 - 02/20/11 03:05 PM Re: Opinon on time machine [Re: ganbustein]
Hal Itosis Offline


Registered: 09/03/09
Loc: 10.6.8 (build 10K549)
Originally Posted By: ganbustein
But I'm not sure what details the ComputerWorld.com article thinks Apple is keeping close to the vest. The Time Machine preference pane (in System Preferences) provides, in 32 words, a very nice summary of how it works that is detailed enough for the vast majority of users.

I'll just <link to the article> then, and quote the specific passage:

Originally Posted By: Ryan Faas

Inside Leopard's Time Machine: Backups for the rest of us (excerpt from page 5):

Finally, it is worth mentioning that Time Machine is very smart in how it determines what to delete when a disk begins to get full. It doesn't simply delete the oldest backups and all their files. Instead, when Time Machine deletes an older backup, it deletes only the files that were unique to that backup (i.e., files that no longer exist anywhere in the file system).

Time Machine also doesn't delete just the oldest backups. While it does keep many recent backups at frequent intervals, it also keeps a range of older backups from a wide range of dates, letting you browse as far back in time as feasible. Exactly what computation goes into determining this approach isn't quite certain (and Apple may have a competitive advantage if it chooses to keep some of Time Machine's secrets close to the vest), but in early testing, it does seem an effective solution.



edit: note that that comes from a very early review, dated October 29, 2007.


Edited by Hal Itosis (02/20/11 03:10 PM)

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#14299 - 02/20/11 06:05 PM Re: Opinon on time machine [Re: Hal Itosis]
roger Offline


Registered: 08/04/09
Loc: Vermont
Originally Posted By: Hal Itosis

Originally Posted By: Ryan Faas
it deletes only the files that were unique to that backup (i.e., files that no longer exist anywhere in the file system).


does anyone else thing that's a bit backward, or am I reading it wrongly? wouldn't you want it to keep the unique files as long as possible, and delete the ones that were available on other backups?
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#14300 - 02/20/11 07:51 PM Re: Opinon on time machine [Re: roger]
Hal Itosis Offline


Registered: 09/03/09
Loc: 10.6.8 (build 10K549)
Originally Posted By: roger
does anyone else thing that's a bit backward, or am I reading it wrongly? wouldn't you want it to keep the unique files as long as possible, and delete the ones that were available on other backups?

Hmm, hard to say (or rather... i'd need to think more before replying wink ).

If a file is unique, then that implies it isn't multi-linked to in any other snapshot. That condition further implies that the item must have been deleted (from the HD) a good while ago [edit: or, alternatively, it didn't exist on the HD for any significant length of time to begin with]... and is therefore more dispensable than other items. [but i know what you're saying... and i'm just guessing myself.]

The other factor is this: it's only by removing unique items that we can free up space. When there are multi-linked items mingling in Time Machine's maze, "removing" one of them merely decrements the link count... thus no actual space gets freed by that process.

Note that Ryan was talking there about when a disk begins to get full.

Looking back on some of the exchanges you've had in this thread, i will say that this unique file business ties in nicely with what MicroMatTech3 said: Time Machine is not an archiver... so make good use of that "extra" folder on the backup disk to store items deleted from the HD. Yes, they do exist (perhaps) in some weekly snapshot... but if they're no longer on the HD, then their heads are on the chopping block when TM needs more room.

--

[i'll probably edit this and say more later. meanwhile, i'm just grateful that ganbustein has a good grip on all this.]

EDIT: i just want to add some thoughts here, because the whole magic behind Time Machine (rsync snapshots) is that it already saves a ton of space by its very nature (the --link-dest option to rsync). Realize that —within the Backups.backupd directory —we eventually accumulate a great number of "snapshots". 23 (???) hourly snapshots, 30 (???) daily snapshots, and an unknown number of weekly snapshots. So we typically have something like over 50 discrete 'versions' of our entire HD sitting there in that folder.

When i used the word 'maze' a few paragraphs back, i meant it. That Backups.backupd directory is no ordinary folder. It contains an intricate matrix of many possible HDs. If you ever try to measure that folder's "size" ...you're in for some fun (depending on which tool you use).


Edited by Hal Itosis (02/20/11 08:39 PM)

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#14301 - 02/20/11 09:49 PM Re: Opinon on time machine [Re: roger]
ganbustein Offline


Registered: 08/04/09
I'd say the clumsy wording comes from ComputerWorld's not having a good understanding about how hard links work.

Suppose you had three files (A, B, and C) on your main volume when TM took its first snapshot. (This is only for the sake of exposition. You'd typically have millions of files.) Those three files would be copied to backup.

Before your second backup, suppose you delete A and add D. For TM's second snapshot, it would copy over the new file, D, and round out the new snapshot by making hard links to B and C. The backup now contains:
Snapshot 1: A(1), B(2), C(2)
Snapshot 2: B(2), C(2), D(1)
where the numbers in parentheses denote the link count, that is, the number of places in the filesystem where the exact same file occurs.

Between then and the third backup, you delete B and add E. The third backup copies the new file E and increments the link counts on the still-present C and D to produce:
Snapshot 1: A(1), B(2), C(3)
Snapshot 2: B(2), C(3), D(2)
Snapshot 3: C(3), D(2), E(1)

There are five physical files (aka inodes) in the backup: A, B, C, D and E. C is listed as C(3) because that one file appears in three snapshots. It's linked to from three directories, so it has three different pathnames, but all three pathnames lead to the same inode. It's a file's inode that contains its data, so the data appears on disk only once.

Suppose we now delete Snapshot 1. In doing that, the reference count of each file in the snapshot is decremented, and any files whose counts go to zero get deleted. This is not unique to Time Machine. It's standard behavior for hard links. In fact, the Unix command rm is really just an alias for unlink, which removes one link from a file and, if and only if that reduces the link count to 0 deletes the underlying inode.

In this case, the only file whose link count goes to zero is A, so that's the only inode that gets deleted. Even though B and C are "removed" (really, "unlinked"), their inodes remain because they're still linked to from snapshots 2 and 3.

This is the behavior that ComputerWorld is talking about when they say
Quote:
Time Machine is very smart in how it determines what to delete when a disk begins to get full. It doesn't simply delete the oldest backups and all their files. Instead, when Time Machine deletes an older backup, it deletes only the files that were unique to that backup (i.e., files that no longer exist anywhere in the file system).
but I repeat that that's nothing smart or clever on TM's part. TM really does just delete the oldest backup; the only cleverness comes from hard links doing what hard links normally do. CW seems to think that deleting Snapshot 1 should physically remove all the inodes it references, and thinks TM is being smart to somehow shield B and C from deletion.

When they refer to "the files that were unique to that backup", they're referring to files like A that are referenced from that backup and no other. The way a file becomes referenced only by the oldest backup is by being a file that was deleted from the main volume longest ago, even before the second-oldest snapshot was taken.

When you later delete Snapshot 2, it'll take with it the inode underlying B, the second file to have been deleted from the main volume. C, D, and E will still remain. Even though C was first backed up with the very first snapshot, and even though it was part of two snapshots that have both been deleted since then, it's still there on the backup (as part of Snapshot 3) because it's still there on the main volume. D was the only file copied to make Snapshot 2, but that's not what they mean by a "file unique to that backup", because D was also made part of Snapshot 3 via hard linking.

The net effect: Time Machine forgets files in the same order you delete them, not the order TM learns about them. (More or less. Any files created and deleted the same day will be forgotten by TM roughly 24 hours after you delete them, when the last hourly snapshot that captured them goes away. Two such files deleted at different times during that day will be forgotten the next day in the same order they were deleted. LIkewise for files created and deleted the same week; TM will forget them a month later, in the same order they were deleted. Files created one week but not deleted until a later week will be remembered as long as possible, but when they are forgotten they'll be forgotten in the order they were deleted.

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#14302 - 02/20/11 10:09 PM Re: Opinon on time machine [Re: ganbustein]
artie505 Online


Registered: 08/04/09
Nice, clear explanation; thanks.

This thread has become a great Time Machine resource.
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In Memory Of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire

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#14304 - 02/20/11 11:34 PM Re: Opinon on time machine [Re: kevs]
artie505 Online


Registered: 08/04/09
Originally Posted By: kevs
So guys, for this to work, my 500GB drive wont work?

I have to buy a new expensive 3TB drive to match the 3TB of data I have?

It just can't start on the cuff backing up data from my new 3TB external hard drive over to my backup 500GB?

I'm not sure I'm willing to buy a new 3tB drive just for time machine when I have an excellent 500GB drive I'm not using.

Is all the data on your 3Tb HD current, or can you archive some/a lot of it elsewhere and start Time Machine with a smaller database?
_________________________
The new Great Equalizer is the SEND button.

In Memory Of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire

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#14306 - 02/21/11 12:17 AM Re: Opinon on time machine [Re: roger]
ganbustein Offline


Registered: 08/04/09
Originally Posted By: roger
does anyone else thing that's a bit backward, or am I reading it wrongly? wouldn't you want it to keep the unique files as long as possible, and delete the ones that were available on other backups?

First, let's agree on terminology.

Suppose you want to create a hierarchical filesystem on top of another filesystem. Call files in the underlying filesystem "inodes" (internal nodes), and their names, as used by the underlying filesystem, "inode names". The only way to access a real file is through its inode name, but you can create hierarchical pathnames of your own choosing.

Start by creating special files called "directories", each of which contains nothing but a map from filename to inode name. Let there be one such directory file, the root directory, whose inode name is well-known. To interpret a pathname like "/a/b/c", look up filename "a" in the root directory to get the inode name for "/a". With that inode name in hand, you can look in that directory file for "b" to get the inode name for "/a/b", and look therein for "c" to get the inode name corresponding to the pathname "/a/b/c".

In the original Unix Filesystem (UFS), the underlying filesystem was as simple as could be. An "inode name" was just a number, indexing into a table of inode descriptors, so in Unix we call it an "inode number" instead of an inode name.

It's quite possible for the same inode number to appear more than once among all the directory files in a system. That's how hard links are created.

In UFS, the directory entry for a filename contains nothing but the corresponding inode number. Everything else about the file is attached to the inode itself: owner, group, permissions, create/modify/access date, flags, size, location on disk, etc. The only thing the inode does not have is a filename. It does, however, contain a link count, a count of the number of times that inode is referenced from any directory anywhere in the system.

All of that is conceptual, of course. Some filesystems, HFS for example, were designed to be hierarchical from the get-go. In HFS, files may but usually do not have inode numbers, directories always have inode numbers even though they have no corresponding inode, being merely records within the catalog and not standalone files. HFS+, among many other changes, requires all file to have inode numbers, and makes hard-linking possible through an elaborate and contrived process.

(Aside: the git version control system also implements hierarchical names the same way, except that an inode's name is a hash of its contents, which is always a valid name in whatever underlying filesystem you're using. This makes all inodes immutable, since the slightest change in content changes the inode name.)

But never mind the mechanics. It's conceptually easier to imagine that even HFS+ works like UFS. When we talk about a "real file" or a "physical file", we mean "inode". When we just say "file", it's ambiguous whether we mean "pathname" or "inode". Thus, if /a/b/c is hard-linked to /d/e, is that one file or two? It's two pathnames, but only one inode, so the answer is different depending on what we mean by "file".

That ambiguity is at the heart of your question.

The original
Quote:
it deletes only the files that were unique to that backup (i.e., files that no longer exist anywhere in the file system).
should have been phrased
Quote:
it deletes only the inodes which had no pathnames outside the backup (i.e., not anywhere else in the file system).


You're thinking it's OK to delete a file that you have other copies of. But if by "file" you mean "inode", you never have other copies. inodes are unique.

If by "file" you mean "pathname", then it's OK to delete a pathname to an inode that's still reachable by other pathnames. As long as any pathname reaches it, the inode remains, the other pathnames still reach it, and no data is lost.

But if the backup you're deleting contains the only remaining pathname to a given inode, then yeah, it's time to delete the inode, because an inode that can no longer be reached is just wasting disk space.


BTW: this tells you how to protect any particular version of file from being purged from backup. Just make a hard link to it, putting the hard link anywhere outside the backup folder. Time Machine let's the normal hard link counting mechanism determine when to delete the inode. Your hard link bumps the link count, and TM can never get it back down to zero.

One drawback is that the inode carries all security with it, including the "group:everyone deny delete" ACL that TM slaps on everything it backs up. You won't be able to easily unlink your new hard link.

Another is that it isn't easy to protect an entire folder this way. HFS+ allows hard links to folders, but I don't know of any unix command line tool that does. You'd probably have to write your own tool in C. (Or some kind soul will chime in and tell us which command to use.)

Soft links won't work. A soft link doesn't bump the link count of the target, so it breaks when the target pathname goes away (even if the target's inode doesn't).

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#14307 - 02/21/11 07:12 AM Re: Opinon on time machine [Re: ganbustein]
roger Offline


Registered: 08/04/09
Loc: Vermont
thank you all. it's making sense to me now.

the references in TM to a "file" (the actual data, say an mp3) are more like aliases, and so deleting them when space is needed is pretty worthless, so of course TM would need to delete the actual file to gain any space. I might have lots of aliases to a particular file within TM, but only one that contains the actual data.

next question: how does one create a "hard link"? I take it that is more than an alias.

thanks again! laugh
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#14308 - 02/21/11 07:13 AM Re: Opinon on time machine [Re: ganbustein]
kevs Offline


Registered: 12/07/09
Artie,
All my data is now on one 3TB drive called Main Hard Drive. ON that drive there is about 2TB of data.

I don't need snapshots of all that 2TB, I could be happy if time machine just backed up some important folders which are well unter 500GB.

But how?

TM options shows all hardrives and partitions on the computer. I tick to exclude the partitions I don't need, but it does not offer the ability to exclude specific folders on Main Hard DRive.

It seems you have to offer up to the TM Gods one hard drive in full, am I wrong? I would love to just offer up a few specific folders from Main Hard Drive and test it out.

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#14309 - 02/21/11 07:32 AM Re: Opinon on time machine [Re: kevs]
artie505 Online


Registered: 08/04/09
Not being a Time Machine aficionado (or even user), but having tried to digest this thread, my best guess is that the only way you can do what you want to do is by partitioning your 3Tb HD, archiving everything that isn't currently important on a really large partition, and keeping your current stuff, the stuff that needs to be TM'ed, on a partition that is small enough for you to work with.

But remember that you'll still need your backup HD to be no less than a Tb, and also remember that, in addition, you'll probably need to reformat your HD.
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