Re: Spurious characters in LVMTAB (67 Views)
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Occasional Contributor
Andy Smith_1
Posts: 6
Registered: ‎01-20-1997
Message 1 of 12 (67 Views)
Accepted Solution

Spurious characters in LVMTAB

are the spurious characters in this lvmtab the result of someone trying to vi it, or do they have a function and if so what ?
/dev/vg00
X]@*1
/dev/dsk/c3t5d0
/dev/dsk/c1t3d0
/dev/vg02
X]@*7j
/dev/dsk/c3t6d0
/dev/dsk/c1t5d0
/dev/vg03
X]@*:
/dev/dsk/c1t6d0
/dev/dsk/c0t6d0
Honored Contributor
T G Manikandan
Posts: 5,533
Registered: ‎12-11-2000
Message 2 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Hello

The type of the lvmtab is 'data'.
YOu cannot do a vi into that.

#strings /etc/lvmtab
should show you the contents.


Thanks
Honored Contributor
steven Burgess_2
Posts: 1,493
Registered: ‎11-21-2001
Message 3 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Hi Andy

I havee seen this on a couple of our boxes. Not sure why it happens though

You can recreate lvmtab by moving it to lvmtab.bak and performing a

vgscan -a

This will recreate lvmtab. The only problem being that it won't be in descending order by volume group

man vgscan

for more options

Hope this helps

Steve
take your time and think things through
Honored Contributor
steven Burgess_2
Posts: 1,493
Registered: ‎11-21-2001
Message 4 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Hi

T G

Have seen this even after

strings /etc/lvmtab

What do you think may be the cause ?

Steve
take your time and think things through
Honored Contributor
T G Manikandan
Posts: 5,533
Registered: ‎12-11-2000
Message 5 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Yes,
you have the volume group with the physical disk information in it.It has the table where the volume groups and the associated physical volumes in each group.
If sometime your lvmtab file is corrupt then
you should do a vgscan -a
to rebuild the lvmtab file.
Honored Contributor
Bill McNAMARA_1
Posts: 3,866
Registered: ‎11-14-2000
Message 6 of 12 (67 Views)

Re: Spurious characters in LVMTAB

These characters are not a problem.
Your lvmtab is not corrupt.
files /etc/lvmtab reports the file is data.

strings /etc/lvmtab extracts the printable characters.. which do not always report just device files.

A vgscan recreation can mess up your pvlinks configuration(alternate paths) very easily causing serious perf degradation.. make sure you know what you're doing.

Later,
Bill
It works for me (tm)
Honored Contributor
Bill McNAMARA_1
Posts: 3,866
Registered: ‎11-14-2000
Message 7 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Looking at your vg03 for example, vgscan will reconfigure it as:

/dev/dsk/c0t6d0
/dev/dsk/c1t6d0

the other vgs will also be swapped. vgscan recreates in numberical order of device file...

Later,
Bill
It works for me (tm)
Honored Contributor
Thierry Poels_1
Posts: 1,218
Registered: ‎08-15-2000
Message 8 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Hi,

/etc/lvmtab is NOT a textfile, and should be edited manually.

"strings /etc/lvmtab" will also show some rubbisch in many cases. "strings" only tries to filter out non-text data, but can never really know what is what.

regards,
Thierry.
All unix flavours are exactly the same . . . . . . . . . . for end users anyway.
Esteemed Contributor
Shahul
Posts: 656
Registered: ‎02-25-2001
Message 9 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Hi

lvmtab is not a text file. It normally contains some unreadable charecters. It is not because of somebody is doing vi. If U doubt like this it is always better to keep a copy of lvmtab. For seeing the contents of lvmtab

#strings /etc/lvmtab

Best of luck
Shahul
Acclaimed Contributor
James R. Ferguson
Posts: 21,184
Registered: ‎07-06-2000
Message 10 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Hi Andy:

The /etc/lvmtab is a binary data file. As noted, 'strings /etc/lvmtab' will expose the printable characters. The file is not and should not be editted manually in any fashion.

The file actually contains the physical device paths for each volume group defined to the system. In addition, the VGID (Volume Group Identification) and some other state information about each volume group is recorded.

As Bill has aptly noted, do *not* capraciously run 'vgscan'. This may reorder the primary and alternate paths to a volume group leading to non-optimal performance. It is the order of the paths in /etc/lvmtab that determines which is a primary and which as an alternate (secondary) pvlink. For vg00, boot information may become incorrect due to reordering of devices following a 'vgscan'. See the 'vgscan' man pages for more information.

Regards!

...JRF...
Honored Contributor
Carlos Fernandez Riera
Posts: 1,172
Registered: ‎09-16-1998
Message 11 of 12 (67 Views)

Re: Spurious characters in LVMTAB

NO problem....


That rare string is part of VGID, and it is recorded on all disks and lvmtab.

No problem.
unsupported
Occasional Advisor
Rafael M. Ferreira
Posts: 5
Registered: ‎06-25-2002
Message 12 of 12 (67 Views)

Re: Spurious characters in LVMTAB

Andy Smith

You don??t open /etc/lvmtab file with vi because it is of the type data file

You can open this file with
strings /etc/lvmtab

Rafael
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