Hi Michael
Thanks for taking the time to write this and share it!
tl
-----Original Message-----
From: EMC NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On
Behalf Of Michael Leone
Sent: Friday, June 03, 2011 12:02 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Consequences of "skip" vs "nul" directives
Here's a cautionary tale about the differences of the "null:" vs "skip:"
directives ...
(this story uses Windows clients as an example, but the concept is
universal, I think)
I have a standard directive I apply to almost all my clients (from within
NMC). It says (among other things):
<< / >>
+null: pagefile.sys
+null: *.MDF *.mdf
+null: *.LDF *.ldf
+null: *.NDF *.ldf
+null: *.LOK *.lok
+null: *.TMP *.tmp
+null: *.LCK *.lck
+null: usrclass.*
+null: ntuser.*
<< "H:\Users" >>
+null: *.MP3 *.mp3
And so I would record the names of those files, but not actually save
them, since they aren't really necessary, and are many times held open by
various process(es)..
So today I am working on a client, and I bring up the GUI nwrecover. I
tell it to select an entire disk drive that was backed up 2 nights ago, I
have it show me the "Required Volumes". And it shows me tapes made 2 days
ago .. and also a tape made in Aug, 2010.
Huh?
Digging deeper, I see a file "~notes.LCK" on that drive, in the list of
files to be recovered. And it shows it's last backup date as 2010-08-31.
This was the reason it was asking for the Aug 2010 tape. Apparently, back
then, I wasn't using this directive (or wasn't using it as currently
configured). Anyway, this file was apparently backed up to tape back then
... and not since. But it still included in the list of files for this
drive, because of the "null:" directive. (the recover list shows it has a
file modification date of 2010-07-31, yet an examination of the actual
drive shows the file with a modification date of 2011-04-14. Apparently,
it gets re-created as needed)
So if I actually had to do a full recover of that drive as of the end of
May, 2011, I would need the tape for May, 2011 ... and the tape for Aug,
2010. BUT .. I wouldn't know I needed the Aug 2010 tape in order to
complete a recovery as of 2 days ago, if all I had done was
mminfo -q "client=xxx,savetime>05/31/2011"
The tape volume list returned does *not* show the Aug 2010 tape ... as of
course, it wouldn't. But I would need to have that tape, else NW would sit
there and ask for it, when I started the recover.
Now, in this specific case, I can change the directive to "skip:", since I
don't need to know about these files, and I don't need to not back them
up. So any recovery I need from this date forward would not ask for that
Aug tape, since that "~notes.LCK" file will not be included in the list of
files backed up from this point forward. But for any (full) recovery of
that drive from a date prior to today, and after Aug 2010, I will also
need to have the Aug 2010 tape .. all because of a silly little lock
file(s) that hasn't been backed up since Aug 2010, but has been included
in the list of files ever since.
I thought that was interesting, if aggravating. And makes me think about
what other unintended side effects might pop up unexpectedly, from the
differences of the "null: and "skip:" directives ...
Just thought I'd share
--
Michael Leone
Network Administrator, ISM
Philadelphia Housing Authority
2500 Jackson St
Philadelphia, PA 19145
Tel: 215-684-4180
Cell: 215-252-0143
<mailto:michael.leone AT pha.phila DOT gov>
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