From Newsgroup: comp.sys.mac.system

What are "cache files"? What do they contain?

I'm wondering because I've noticed that when I tell Retrospect to do an incremental backup, it decides that it needs to back up around 3GB worth
of files, even if I've only done only a little bit of Email since the
last backup. In fact, if I complete a backup and then immediately fire
off a new backup, it concludes that it needs to back up nearly 400Meg!

I'm telling it to back up "all but cache files," but I've noticed that
many of the files it backs up are named of the form
"<digits>.<digits>.cache". I presume those must be "cache files,"
whatever they are...

This is Retrospect version 6.0.212 on my 17" G4 PowerBook. It doesn't
do this with a similar backup on my Dual-G5 machine.

--

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From Newsgroup: comp.sys.mac.system

In article <lLV1g.13440$0Z4.147@tornado.texas.rr.com>,
Gary Morrison <mr88cet@texas.net> wrote:

What are "cache files"? What do they contain?

I'm wondering because I've noticed that when I tell Retrospect to do an incremental backup, it decides that it needs to back up around 3GB worth
of files, even if I've only done only a little bit of Email since the
last backup. In fact, if I complete a backup and then immediately fire
off a new backup, it concludes that it needs to back up nearly 400Meg!

I'm telling it to back up "all but cache files," but I've noticed that
many of the files it backs up are named of the form "<digits>.<digits>.cache". I presume those must be "cache files,"
whatever they are...

This is Retrospect version 6.0.212 on my 17" G4 PowerBook. It doesn't
do this with a similar backup on my Dual-G5 machine.

From the Terminal, type the following commands:

find /Library/Caches
find ~/Library/Caches

see all those files ending with .cache or the files in the Metadata directories on Tiger? Those are cache files.

--
DeeDee, don't press that button! DeeDee! NO! Dee...



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From Newsgroup: comp.sys.mac.system

Michael Vilain wrote:

see all those files ending with .cache or the files in the Metadata directories on Tiger? Those are cache files.

OK, but what are they? What creates them (the OS, some application,
or...)? What purpose do they serve? Is there something I'm doing to
create, or modify, a lot of them? Do any of you have any guesses as to
why Retrospect would back them up when I told it to back up all but
cache files?

--

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From Newsgroup: comp.sys.mac.system

In article <WbY1g.13620$0Z4.6459@tornado.texas.rr.com>, Gary Morrison <mr88cet@texas.net> wrote:

Michael Vilain wrote:

see all those files ending with .cache or the files in the Metadata directories on Tiger? Those are cache files.

OK, but what are they? What creates them (the OS, some application,
or...)?

The OS.

What purpose do they serve?

To make things happen faster.

Is there something I'm doing to
create, or modify, a lot of them?

Other than using the computer, no.

Do any of you have any guesses as to
why Retrospect would back them up when I told it to back up all but
cache files?

Its selector for excluding cache files probably doesn't exclude
absolutely everything that's a cache. You can modify the selectors so
they exclude the files you don't want backed up. There's no need to
back up cache files as they will be reproduced when necessary. I also
exclude logs from my primary backup.

--
Jerry Kindall, Seattle, WA <http://www.jerrykindall.com/>

Send only plain text messages under 32K to the Reply-To address.
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From Newsgroup: comp.sys.mac.system

Gary Morrison <mr88cet@texas.net> wrote:

Michael Vilain wrote:

see all those files ending with .cache or the files in the Metadata directories on Tiger? Those are cache files.

OK, but what are they? What creates them (the OS, some application,
or...)? What purpose do they serve? Is there something I'm doing to
create, or modify, a lot of them? Do any of you have any guesses as to
why Retrospect would back them up when I told it to back up all but
cache files?

Caches contain temporary storage, such as web pages you've visited. It
enables the browser to quickly to back to a page during a session, by
loading the page from the cache, rather than from the internet. There is
no need to back-up cache folders.

I too have seen that Retrospect still backs up cache files, even if you
choose the option not to do so. I guess it's a bug.


--
Johan W. Elzenga johan<<at>>johanfoto.nl
Editor / Photographer http://www.johanfoto.nl
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From Newsgroup: comp.sys.mac.system

Johan W. Elzenga wrote:

Caches contain temporary storage, such as web pages you've visited.

Are you sure they're browser cache files? It seems curious that they
wouldn't be in a folder specific to Safari or whatever other browser.
Another reply suggested that the OS creates them to cache ... well,
something else.

--

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From Newsgroup: comp.sys.mac.system

Jerry Kindall wrote:

OK, but what are they? What creates them (the OS, some application, >>or...)?

The OS.

What purpose do they serve?

To make things happen faster.

What things do they make faster? What sort of information do they
cache? For example, are they VM page files?

--

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From Newsgroup: comp.sys.mac.system

In article <200420062033573565%jerrykindall@nospam.invalid>,
Jerry Kindall <jerrykindall@nospam.invalid> wrote:

The OS.

And certain applications.

--
We are the music makers, And we are the dreamers of dreams,
Wandering by lone sea-breakers, And sitting by desolate streams.
from "Ode", Arthur O'Shaughnessy
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From Newsgroup: comp.sys.mac.system

In article <1he540z.1y04syj1mgfhs0N%nomail@please.invalid>,
nomail@please.invalid (Johan W. Elzenga) wrote:

I too have seen that Retrospect still backs up cache files, even if you choose the option not to do so. I guess it's a bug.

Yes, an incomplete specification. The existing spec is pretty long, but
I added

Or File Name ends with "cache"

which seems to have fixed it.

--
We are the music makers, And we are the dreamers of dreams,
Wandering by lone sea-breakers, And sitting by desolate streams.
from "Ode", Arthur O'Shaughnessy
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From Newsgroup: comp.sys.mac.system

Gary Morrison <mr88cet@texas.net> wrote:

Johan W. Elzenga wrote:

Caches contain temporary storage, such as web pages you've visited.

Are you sure they're browser cache files? It seems curious that they wouldn't be in a folder specific to Safari or whatever other browser.
Another reply suggested that the OS creates them to cache ... well, something else.

"Such as" means that browser cache is only one example of a cache. If
you look into 'Home/Library/Caches you'll see that there are many
applications that use a cache.


--
Johan W. Elzenga johan<<at>>johanfoto.nl
Editor / Photographer http://www.johanfoto.nl
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From Newsgroup: comp.sys.mac.system

Howard S Shubs <howard@shubs.net> wrote:

In article <1he540z.1y04syj1mgfhs0N%nomail@please.invalid>,
nomail@please.invalid (Johan W. Elzenga) wrote:

I too have seen that Retrospect still backs up cache files, even if you choose the option not to do so. I guess it's a bug.

Yes, an incomplete specification. The existing spec is pretty long,

IMHO, many of Retrospect's supplied Selectors are unduly complex and can produce surprising results, especially when you end up with double or
nested exclusions -- using as one of a script's exclusionary conditions
a Selector that itself contains one or more exclusionary conditions.

I've found it best to create a set of simple and inclusionary Selectors
and to build more complicated rule sets from them either in the scripts themselves or in Selectors of Selectors. To test an inclusionary
Selector as an exclusionary rule, you can create a special "Test"
Selector to use that Selector as an "exclude" criterion.

but I added

Or File Name ends with "cache"

which seems to have fixed it.

That condition, plus Enclosing Folder matches "Caches", catches
essentially all cache-type files, including those in ~/Library/Icons.
The only caveat is that it also matches a few items that are part of application packages and such. Very few true cache files exist outside
users' home folders, so you don't really need to exclude them when
backing up system or application files.

I hope everybody caches my drift.

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From Newsgroup: comp.sys.mac.system

Neill Massello <neillmassello@earthlink.net> wrote:

That condition, plus Enclosing Folder matches "Caches", catches
essentially all cache-type files, including those in ~/Library/Icons.
The only caveat is that it also matches a few items that are part of application packages and such. Very few true cache files exist outside
users' home folders, so you don't really need to exclude them when
backing up system or application files.

The real problem, in my view, is that Retrospect's interface is so
crappy. There's no way to have Retrospect start a contemplated backup
and then say to it, "please highlight all the files on the computer that
are included in the "Cache" exclusionary rule, so that I may see what it
does in practice." m.


--
matt neuburg, phd = matt@tidbits.com, http://www.tidbits.com/matt/
Tiger - http://www.takecontrolbooks.com/tiger-customizing.html
AppleScript - http://www.amazon.com/gp/product/0596102119
Read TidBITS! It's free and smart. http://www.tidbits.com
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From Newsgroup: comp.sys.mac.system

matt neuburg <matt@tidbits.com> wrote:

The real problem, in my view, is that Retrospect's interface is so
crappy. There's no way to have Retrospect start a contemplated backup
and then say to it, "please highlight all the files on the computer that
are included in the "Cache" exclusionary rule, so that I may see what it
does in practice." m.

Well, you can "Check Selector" to see a list of items that will be
selected from a target volume or subvolume; and you can view a backup
set's contents, snapshot by snapshot, after the fact. But yes,
Retrospect's interface is a convoluted, confusing, click-happy mess. I
can't think of a major Mac app more in need of complete interface
overhaul.

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From Newsgroup: comp.sys.mac.system

Neill Massello <neillmassello@earthlink.net> wrote:

matt neuburg <matt@tidbits.com> wrote:

The real problem, in my view, is that Retrospect's interface is so
crappy. There's no way to have Retrospect start a contemplated backup
and then say to it, "please highlight all the files on the computer that are included in the "Cache" exclusionary rule, so that I may see what it does in practice." m.

Well, you can "Check Selector" to see a list of items that will be
selected from a target volume or subvolume; and you can view a backup
set's contents, snapshot by snapshot, after the fact. But yes,
Retrospect's interface is a convoluted, confusing, click-happy mess.

You forgot slow. Getting it to open or close one of those disclosure
triangle thingies in the hierarchical file display is like pulling
teeth. m.

--
matt neuburg, phd = matt@tidbits.com, http://www.tidbits.com/matt/
Tiger - http://www.takecontrolbooks.com/tiger-customizing.html
AppleScript - http://www.amazon.com/gp/product/0596102119
Read TidBITS! It's free and smart. http://www.tidbits.com
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From Newsgroup: comp.sys.mac.system

In comp.sys.mac.system Neill Massello <neillmassello@earthlink.net> wrote:

That condition, plus Enclosing Folder matches "Caches", catches
essentially all cache-type files, including those in ~/Library/Icons.
The only caveat is that it also matches a few items that are part of application packages and such.

It will also exclude backing up some files which are actually not
caches, like these:

/Library/Caches/com.apple.user501pictureCache.tiff /Library/Caches/com.apple.user502pictureCache.tiff /Library/Caches/com.apple.user503pictureCache.tiff

These are your user login pictures. If you have some custom ones that
you really like and are not easily replaced, they won't get backed up by excluding "Enclosing folder contains 'Cache'" with Retrospect.

I just back up everything, caches and all. Storage is cheap these days.
Why take the risk of missing something that might be important?

--
K.
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From Newsgroup: comp.sys.mac.system

In article <1he5czm.1nxzvrj1xzrjy8N%neillmassello@earthlink.net>,
neillmassello@earthlink.net (Neill Massello) wrote:

I hope everybody caches my drift.

Where? If we do, it won't get backed up.

--
We are the music makers, And we are the dreamers of dreams,
Wandering by lone sea-breakers, And sitting by desolate streams.
from "Ode", Arthur O'Shaughnessy
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From Newsgroup: comp.sys.mac.system

In article <Pjd2g.1211$8E1.631@clgrps13>, me@home.spamsucks.ca (Király)
wrote:

It will also exclude backing up some files which are actually not
caches, like these:

/Library/Caches/com.apple.user501pictureCache.tiff /Library/Caches/com.apple.user502pictureCache.tiff /Library/Caches/com.apple.user503pictureCache.tiff

Nope. Those filenames don't end in "cache". They end in "tiff".

--
We are the music makers, And we are the dreamers of dreams,
Wandering by lone sea-breakers, And sitting by desolate streams.
from "Ode", Arthur O'Shaughnessy
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From Newsgroup: comp.sys.mac.system

In article <BJ32g.16414$0Z4.1624@tornado.texas.rr.com>,
Gary Morrison <mr88cet@texas.net> wrote:

Jerry Kindall wrote:

OK, but what are they? What creates them (the OS, some application, >>or...)?

The OS.

What purpose do they serve?

To make things happen faster.

What things do they make faster? What sort of information do they
cache? For example, are they VM page files?

An example is that web browsers save the files that they've downloaded.
If you try to download the same file again, the browser can get it from
the file on disk instead of going out to the web server again. This is particularly useful for images and icons that are used repeatedly at
different places on a web site.

The general idea of cache files is that they are temporary files that
save something that would be slow to recreate. But they're not
important to back up, because you *can* recreate them if necessary.

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***
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From Newsgroup: comp.sys.mac.system

In article <BJ32g.16414$0Z4.1624@tornado.texas.rr.com>, Gary Morrison <mr88cet@texas.net> wrote:

Jerry Kindall wrote:

OK, but what are they? What creates them (the OS, some application, >>or...)?

The OS.

What purpose do they serve?

To make things happen faster.

What things do they make faster? What sort of information do they
cache? For example, are they VM page files?

Various different things. For outline font caches, it might be
pre-rendered bitmaps. That way when you want, say, 12 point Times New
Roman, it doesn't need to be rendered from the outline font each time.
Icons are also cached by the Finder, so that rather than having to find
the application each time an icon is needed (say, a Word document icon,
which is defined in the Word application bundle) the icons are all
stored in one place. There's a cache for kernel extensions, so the OS
doesn't have to look through each kext at startup time to find out the information it needs. Applications may also have their own caches --
for example, iPhoto caches low-res version of your photos so it doesn't
have to read the entire photo each time it displays a thumb. Etc...

--
Jerry Kindall, Seattle, WA <http://www.jerrykindall.com/>

Send only plain text messages under 32K to the Reply-To address.
This mailbox is filtered aggressively to thwart spam and viruses.
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From Newsgroup: comp.sys.mac.system

In comp.sys.mac.apps Howard S Shubs <howard@shubs.net> wrote:

/Library/Caches/com.apple.user501pictureCache.tiff /Library/Caches/com.apple.user502pictureCache.tiff /Library/Caches/com.apple.user503pictureCache.tiff

Nope. Those filenames don't end in "cache". They end in "tiff".

Reread my post. I was responding specifically to the part where the
previous poster said to exclude backing up 'Enclosing Folder matches "Caches"'.

--
K.
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From Newsgroup: comp.sys.mac.system

Jerry Kindall wrote:

Various different things.

Ah. So all of those different things go under one classification of
cache files. Interesting...

Thanks for the replies!

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From Newsgroup: comp.sys.mac.system

Johan W. Elzenga wrote:

"Such as" means that browser cache is only one example of a cache.

OK, good point. The idea that it a wide variety of different kinds of
things could be cached in that one place there hadn't occurred to me.

Thanks for the replies.

--

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From Newsgroup: comp.sys.mac.system

Howard S Shubs wrote:

Yes, an incomplete specification. The existing spec is pretty long, but
I added
Or File Name ends with "cache"
which seems to have fixed it.

That did indeed help.

After I looked at the snapshots in greater detail, however, I noticed
that the largest single offender was Spotlight's file-content index
file. On this particular machine, it worked out to nearly 300Meg, so I
told Retrospect to not back that up. Spamfire's databases were also
pretty big, so I told it to exclude them too. I'll just catch them with
my external-firewire-drive backups I do every couple weeks or so.

--

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From Newsgroup: comp.sys.mac.system

In article <8Yx2g.25466$ZB1.1968@tornado.texas.rr.com>,
Gary Morrison <mr88cet@texas.net> wrote:

Johan W. Elzenga wrote:

"Such as" means that browser cache is only one example of a cache.

OK, good point. The idea that it a wide variety of different kinds of things could be cached in that one place there hadn't occurred to me.

What "one place" are you talking about? If you look at the Cache Files selector, you'll see that it lists around two dozen different patterns
of filenames and folders. They've tried to recognize cache files used
by many different applications. Some of these may no longer exist --
the selector has been part of Retrospect for many years, predating OS X,
and I don't think they've tried to clean it up -- they just keep adding
things to it as they learn about them.

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***
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