SUMMARY: Is data still "good" after rewriting disk label?

From: Paul N. Youngblood <youngbp_at_email.uah.edu>
Date: Mon, 02 Mar 1998 11:30:52 -0600 (CST)

Hello managers,

I got several very speedy replies to my question. My original
submission is at the end of this summary. Just about everyone
said that I could re-write the label to enlarge the swap space
without losing the partition I want to keep. This is because
I would NOT be changing the offset, size, or fstype of the
critical partition. However, everyone also said to definitely
make a backup beforehand, just in case something does go wrong.
THANKS VERY MUCH to the following people for thier responses and
for making this list such a terrific resource:

   Erik Persson <erik_at_ikp.liu.se>
   Alan Davis <Alan.Davis_at_digital.com>
   Alan Rollow <alan_at_nabeth.cxo.dec.com>
   Berry Kercheval <berry_at_join.com>
   Rodrigo Poblete <rpoblete_at_gmd.com.pe>
   Kurt Carlson <snkac_at_java.sois.alaska.edu>
   George Guethlein <GGuethlein_at_GiantOfMaryland.com>
   Jim Belonis <belonis_at_dirac.phys.washington.edu>
   Russel Morison <russel_at_maths.unsw.EDU.AU>
   Dr. Tom Blinn <tpb_at_zk3.dec.com>

ADDITIONAL THANKS to Rodrigo Poblete for pointing out that I'll
need to use the "-t advfs" option on the disklabel command when
I rewrite the label because it is the system disk.

And ADDITIONAL THANKS to the following for pointing out that my
AFTER label was incorrect (from the "Proposed Layout" in my
original query posting):

   Kurt Carlson
   George Guethlein
   Dr. Tom Blinn

In my original incorrect version, I had moved the offset of my
swap partition and made its size the same as before -- what I
really wanted to do was leave the offset where it was and DOUBLE
the size of my swap by expanding it into an adjacent (unused)
partition. Here's the corrected layout:

****** Proposed Layout ******
8 partitions:
# size offset fstype [fsize bsize cpg]
  a: 945764 0 AdvFS # (Cyl. 0 - 1185*)
  b: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  c: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  d: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  e: 1105096 945764 swap # (Cyl. 1185*- 2569*)
  f: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  g: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  h: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
---------------------------------------------------------------------

Below, please find my original question.

Paul Youngblood
University of Alabama in Huntsville
youngbloodp_at_uah.edu

---------------------------------------------------------------------
ORIGINAL POSTING:
---------------------------------------------------------------------

Hello managers,

If I use disklabel to rewrite the label of my boot disk in order to
enlarge swap into an unused partition, will the data in the unaffected
partition remain intact and usable? Or, will I need to restore the
critical partition from tape after rewriting the label?

I'm running DU 4.0B with C2 Security and all AdvFS file systems on
an AlphaServer 2100. My root domain is on the "a" partition of an
RZ26 disk. There are no other file systems on the disk. Swap space
begins at the partition adjacent to the "a" partition. Please see
my current layout from part of the disk label below. After that is
my proposed rewritten layout for the disk label.


****** Current Layout ******
8 partitions:
# size offset fstype [fsize bsize cpg]
  a: 945764 0 AdvFS # (Cyl. 0 - 1185*)
  b: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  c: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  d: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  e: 552548 945764 swap # (Cyl. 1185*- 1877*)
  f: 552548 1498312 unused 1024 8192 # (Cyl. 1877*- 2569)
  g: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  h: 0 0 unused 1024 8192 # (Cyl. 0 - -1)

****** Proposed Layout ******
8 partitions:
# size offset fstype [fsize bsize cpg]
  a: 945764 0 AdvFS # (Cyl. 0 - 1185*)
  b: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  c: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  d: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  e: 552548 1498312 swap # (Cyl. 1185*- 2569*)
  f: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  g: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
  h: 0 0 unused 1024 8192 # (Cyl. 0 - -1)
---------------------------------------------------------------------
Thanks for any suggestions you can provide. I'll summarize.
Received on Mon Mar 02 1998 - 18:23:08 NZDT

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