Subject: Re: netatalk in production environments...Definitive
From: Sak Wathanasin (sw@nan.co.uk)
Date: Thu Jun 01 2000 - 06:40:29 EDT
In reply to Luke McNeilage's message of the 01/06/2000 at 17:43 +1000,
>On one Macintosh make an alias of a file off my NT server.
>Store that alias three directories deep.
>open that directory on another Macintosh.
>double click on the alias,
>and it will prompt me to login to the NT Server.
Um, if you bothered to read the list like you tell everyone to, you'd
know that NT file services for Macintosh is one of the few to support
file and directory IDs (ie aliases to you).
On netatalk volumes, for example, aliases to a folder inside a volume
work fine until you do something to change the directory structure.
Try this:
1) create a folder on a netatalk vol, call it test
2) make an alias to it onto a local disk
3) dbl-click on the alias and it should open the folder on the
mounted vol; unmount the netatalk vol, dbl-click the alias and it
should re-mount the netatalk volume for you. So far so good
4) Now create a new folder called test1,and move the test folder
inside the new one
5) dbl-click the alias and check that it still works (cool, no?
Sym-links don't do this.)
6) Now re-boot the Mac; when it comes back up, dbl-click on the the
alias. It will either say it can't be found, open a completely
different folder or if you're dead lucky it will re-open the test
folder. It all depends on whether netatalk has re-assigned it the
same directory ID. In the case of the last, create another folder,
test2, move the test folder to it, delete test1, reboot and try
again. It will fail eventually.
If this test sounds artificial, remember that on a busy server, users
will be creating and deleting folders all the time.
As for:
>Its ill-advised information like this that causes distress
>
>Quark does not save aliased link, and the Mac OS just works more efficiently
I'm sorry I picked a bad example in Quark: my memory isn't what it
was or perhaps they've changed the file format since I last did any
serious work with Q Express (v3! I was debugging an OPI server and QX
gave us no end of grief, but that's another story). If I'd been
thinking I would have realized that none of the appls with
cross-platform file formats would keep alias records* in their data
files (since this would not be supported on other platforms).
Nevertheless, there are plenty of Mac appls that do esp in prefs
files. For example, Apple- (nee Claris-) Works uses alis records to
locate its spelling dictionaries. So if a bunch of users wanted to
share a common dict on a netatalk volume, too bad. And so on.
My point is that as a user, you have no control over this. It's great
that most of the commonly used appls don't do this, but as a
sysadmin, you can be pretty sure that some user will ring you up one
day and say, "the XXX appl works if I sav eto my disk but not the
file server". Of course, Murphy's law says that it will be your boss
or biggest client and it will be their favourite PIM/drawing
program/something absolutely essential.
Why do appls use alis records to track files? For one thing,
pathnames aren't sufficient on MacOS: you can have more than 1
mounted volume with the same name. Besides, Apple tells you to -
there's a tech note somewhere that recommends to developers that
appls save alis'es instead of pathnames.
* See chapter 4 of "Inside Macintosh: Files"
-- Sak Wathanasin Network Analysis Limited 178 Wainbody Ave South, Coventry CV3 6BX, UKInternet: sw@nan.co.uk Phone: (+44) 24 76 41 99 96 Mobile: (+44) 79 70 75 19 12 Fax: (+44) 24 76 69 06 90
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