Contents of /etc/lvmtab

[CelesteG]

Hello everyone. I had a question concerning the /etc/lvmtab. I just added a new vdisk from our SAN to one of our application servers which is an rp3440, running HP 11i.

After the disk was added this is the what was added to the /etc/lvmtab

/dev/vg04
GWVl
/dev/dsk/c10t0d2

I've never seen a line like 'GWV1' in the /etc/lvmtab before and was wondering if anyone has seen that before. The vdisk that I added is working fine, all the pv/vg/lv commands worked and the file system has been mounted and reporting no errors. Just feeling a little uneasy about this entry in my lvmtab.

Thanks for your advise.

Celeste

[A. Clay Stephenson · Accepted solution]

I assume that this was your output from "strings /etc/lvmtab". You have to understand that lvmtab is a binary file that also happens to contain some printable ASCII data. You also have to understand that the strings command interprets any 3 or more consecutive printable ASCII characters as text and outputs up to the first non-printable ASCII character so that what you see is completely expected. You are using a tool to view binary data that often works well but sometimes outputs what appears to be extraneous data to us dumb humans.

There's nothing wrong.

[Jim Mallett]

Nothing to worry about Celeste. The /etc/lvmtab file is binary, and there happen to be some characters (not pertaining disk devices) that are ascii characters.

Many of my LVs show the same:
# strings /etc/lvmtab
...
/dev/bcv_vg05
dM@EkHI
/dev/dsk/c40t0d3
/dev/bcv_vg06
/dev/dsk/c40t0d4
dM@EkHL
...

You can play around with the strings command and possible remove some of the unwanted data, e.g.
# strings -n 10 /etc/lvmtab
...
/dev/bcv_vg05
/dev/dsk/c40t0d3
/dev/bcv_vg06
/dev/dsk/c40t0d4
...

Careful though, if you have short VG names, it may exclude them.

Hope this helps...
Jim

[Yogeeraj_1]

hi Celeste,

As mentioned above, the lvmtab is a binary file and there is nothing you have to worry about the output you are getting.

of you want to know which disks are being used by the current Volume groups you can also run:
e.g.
# vgdisplay -v|grep "PV Name"
PV Name /dev/dsk/c1t0d0
PV Name /dev/dsk/c1t2d0
PV Name /dev/dsk/c2t0d0
PV Name /dev/dsk/c6t0d1
PV Name /dev/dsk/c6t1d0
PV Name /dev/dsk/c6t0d2
PV Name /dev/dsk/c6t1d1
PV Name /dev/dsk/c6t0d3
PV Name /dev/dsk/c6t0d7
PV Name /dev/dsk/c6t0d6
#


kind regards
yogeeraj

[CelesteG]

Whew! Thanks a bunch for putting my minde at ease and for the additional the info! Yes I was the using 'strings' command to view the contents of the lvmtab file, apologies for not including that.

Thanks again.

[Torsten.]

As mentioned before, the lvmtab is binary.

# file /etc/lvmtab
/etc/lvmtab: data

# >od -c /etc/lvmtab
0000000 003 350 \0 \0 \0 \0 \0 001 \0 \0 \0 \0 / d e v
0000020 / v g 0 0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0
0000040 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0
*
0002000 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 x \f + S
0002020 D 026 222 i \0 \0 \0 \0 \0 \0 \0 \0 \0 001 \0 \0
0002040 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 / d e v / d
0002060 s k / c 0 t 6 d 0 \0 \0 \0 \0 \0 \0 \0
0002100 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0
*
0004056

Now compare to

# >strings /etc/lvmtab
/dev/vg00
/dev/dsk/c0t6d0


The formatting here in html may be bad, but you can read the same output in the "od" result.