Original question:
>Can I use slice 2 (s2) of the disk, changing it as I want ( size, start cylinder )?
>Can it be correct for every task? Can it cause any problem?
>I know s2 is used as a whole disk for backup. In manuals it only says :
>
>"Refers to the entire disk, by convention.
>It is defined automatically by Sun's
>format and the Solaris installation
>programs. The size of this slice should
>not be changed."
Our problem was in follows:
>unix: fas: 10.0: cdb=[ 0x2a 0x0 0x0 0xce 0xcc 0x2 0x0 0x0 0x40 0x0 ]
>unix: fas: 10.0: cdb=[ 0x2a 0x0 0x0 0xce 0xd3 0x42 0x0 0x0 0x40 0x0 ]
>unix: fas: 10.0: cdb=[ 0x2a 0x0 0x0 0xce 0xd3 0xd2 0x0 0x0 0x40 0x0 ]
>unix: fas: 10.0: cdb=[ 0x2a 0x0 0x0 0xce 0xd4 0x52 0x0 0x0 0x40 0x0 ]
>unix: fas: 10.0: cdb=[ 0x2a 0x0 0x0 0xce 0xd5 0x62 0x0 0x0 0x40 0x0 ]
>unix: WARNING: /sbus@3,0/SUNW,fas@3,8800000 (fas0):
>unix: Connected command timeout for Target 10.0
>unix: WARNING: /sbus@3,0/SUNW,fas@3,8800000 (fas0):
>unix: Target 10 reducing sync. transfer rate
>unix: WARNING: /sbus@3,0/SUNW,fas@3,8800000/sd@0,0 (sd15):
>unix: SCSI transport failed: reason 'reset': retrying command
>unix: WARNING: /sbus@3,0/SUNW,fas@3,8800000/sd@a,0 (sd24):
> ^^^^^^^
>unix: SCSI transport failed: reason 'timeout': retrying command
>unix: WARNING: /sbus@3,0/SUNW,fas@3,8800000/sd@a,0 (sd24):
> ^^^^^^^
>unix: SCSI transport failed: reason 'reset': retrying command
>unix: WARNING: /sbus@3,0/SUNW,fas@3,8800000/sd@b,0 (sd25):
>unix: SCSI transport failed: reason 'reset': retrying command
>unix: WARNING: /sbus@3,0/SUNW,fas@3,8800000/sd@a,0 (sd24):
> ^^^^^^^
>unix: SCSI transport failed: reason 'incomplete': retrying command
>unix: WARNING: /sbus@3,0/SUNW,fas@3,8800000/sd@a,0 (sd24):
> ^^^^^^^
>unix: disk not responding to selection
The system was in hanging state all the time after such messages.
We used s2 for oracle raw device ( part of the disk )
sd24:
^^^^^
Part Tag Flag Cylinders Size Blocks
0 unassigned wu 2 - 458 801.31MB (457/0/0) 1641087
1 unassigned wu 459 - 1043 1.00GB (585/0/0) 2100735
2 unassigned wu 1044 - 1628 1.00GB (585/0/0) 2100735 #as a raw device for oracle
^^^^^^
3 unassigned wu 1629 - 2797 2.00GB (1169/0/0) 4197879
4 unassigned wm 2798 - 4923 3.64GB (2126/0/0) 7634466
5 unassigned wm 0 0 (0/0/0) 0
6 unassigned wm 0 0 (0/0/0) 0
7 unassigned wm 0 0 (0/0/0) 0
But we don`t consider that s2 is a cause of errors.
We just replace this disk with new one & don't use s2.
So far it works.
We don`t test old disk jet but we think it can be bad.
.......................................................................................
Many suggestions about s2 have come. But they are so different.
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From: Casper Dik <casper@holland.Sun.COM>
s2 is not used for backup. The slices w/ filesystems are used
for backup
If you need 8 partitions, you could reassign slice 2, but I'm not sure
if upgrade likes that.
.......................................................................................
From: nobroin@sced.esoc.esa.de (Niall O Broin)
Best not to - adhere to the convention as you quoted from the manual.
Probably - so just don't use it !
I hope this doesn't mean that you think that backing up s2 using ufsdump will dump
the entire disk, because it doesn't. Ufsdump is filesystem based, so if you do a
ufsdump of e.g. /dev/dsk /c0t0d0s2 whcat you will actually do is a ufsdump of
whichever slice starts at block zero, usually of course s0.
.......................................................................................
From: "Ackerson, Greg" <ackerson_ga@nns.com>
Gosh! I can't even fathom the consequences of trying to redefine what slice2
is. That sounds either impossible or tremendously dangerous.
If you want to refer to the entire physical disk, disregarding partitions,
then you would point to slice2... but we've never needed to do that because
we use Solstice DiskSuite or Veritas Volume Manager to handle that.
Really, as far as changing the size is concerned, I figure one of two things
happening: if you shrink the size, you lose usable disk space; and if you
enlarge it, you get horrendous errors (and even if you do eke out additional
space, you would be exceeding manufacturer-set safe limits).
.......................................................................................
From: Derek Terveer <derek.terveer@ci.saint-paul.mn.us>
I have and I have not had any problems. However, I have not used any sun or
other commercial backup programs that might assume that this slice exists as
defined by default. You should check each application that has access to
the disk slices, but I don't think that there are many that make use of it...
.......................................................................................
From: "Dwight Peters" <dpeters@nswc.navy.mil>
Yes you can, but you don't want to. The convention is real strong. If you
start using slice 2 for your own purposes you will have to rewrite a whole lot
of code that assumes that slice two follows the conventions.
.......................................................................................
From: olovyann@pfizer.com (Oleg Olovyannikov)
You should only use s2 to refer to the entire disk; for example, if you
wished to copy the entire contents of one disk to another, you could do
something like: dd if=/dev/rdsk/c0t0d0s2 of=/dev/rdsk/c1t0d0s2 bs=1024k.
Otherwise, you should leave it alone; think of slice two as the representation
of the whole disk -- a sum of all the cylinders of s0, s1, s3, s4, s5, s6, and
s7. Changing s2 WILL cause problems; the OS will have an incorrect idea of the
size, boundaries, partitions, free space, etc., of the disk. You will lose
either the beginning or the end of the disk.
More importantly, remember that the VTOC (volume table of contents) resides on
cylinder 0 of the disk (use the command "prtvtoc /dev/rdsk/c?t?d?s2" to view it
(here's another example of the use of slice 2). This is VITAL information, as it
contains the partition map, the filesystem information, the formatting
information, such as the number of cylinders, sectors per cylinder, bytes per
sector, etc.
In short, slice two should simply reflect the entire disk from cylinder 0 to the
end; you should never change it, only use it with appropriate commands.
.......................................................................................
From: klfergason@amoco.com (Kelly Fergason)
My opinion: if you know what you are doing, you can use it.
The only reason to use slice 2 is if you need 8 partitions.
.......................................................................................
From: Chris Marble <cmarble@orion.ac.hmc.edu>
Sure, you can set up disks any way that you want. Any partition, any
place, any size. It's only when it's your boot drive, it's died and
you're booting off CD-ROM that being so non-standard could cause
problems. If it's a data disk then you should never have a problem.
.......................................................................................
From: Larry Zins <lzins@lucent.com>
It's ok to use slice 2 if you use the whole disk, but I would not alter it to
a smaller size.
.......................................................................................
From: "Peter L. Wargo" <plw@ncgr.org>
Ummm... *bad* idea to play with s2. (or slice "c" to us old folks...)
It refers to the whole disk, many bad things will happen if you muck with it.
Better to use another slice. By default, I usually use slice 7 to refer to the
whole disk as a partition. In other words, make slice 7 look like slice
2, then refer to 7 when you newfs it.
.......................................................................................
From: "Brion Leary" <brion@dia.state.ma.us>
You can use slice 2. Changing it's size is safe.
You should not change it unless you need too.
The problems come when someone else administers the machine.
.......................................................................................
From: Angel Ortiz <cherub@lava.net>
>From I have read/found this partition can be renamed and used with minor
side effects. One side effect is that you cannot do "dd" and copy the
whole disk on one single swoop.
But if you do not have any intentions of copying the disk, then it is
alright to use that partition as well...
.......................................................................................
From: a.chan@cdnair.ca (Alan Chan)
It will work, but not recommended.
.......................................................................................
From: Chris Liljenstolpe <cds@mcmurdo.gov>
I would follow the manual's suggestions. You can make a file
sytem on it, if you want to, but DO NOT change the size, etc.
.......................................................................................
From: blymn@baea.com.au (Brett Lymn)
You can use it but it is not recommended. Some tools (like prtvtoc)
make an assumption that s2 is the whole disk and their reports are
incorrect if this is not the case.
.......................................................................................
From: "O'Neal,Chris" <onealwc@AGEDWARDS.com>
Typical s2 is left alone
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The end.
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