topic Re: Space in lvol in Operating System - HP-UX

Space in lvol

Carme Torca — Fri, 27 Sep 2002 12:20:03 GMT

Hi,

I have two servers, and the two with the same problem. When I do bdf, it shows me

> bdf
Filesystem kbytes used avail %used Mounted on
/dev/vg00/lvol3 83733 40327 35032 54% /
/dev/vg00/lvol1 47829 18749 24297 44% /stand
/dev/vg00/lvol8 680323 387961 224329 63% /var
/dev/vg00/lvol7 504547 367045 87047 81% /usr
/dev/vg00/lvol4 30597 5726 21811 21% /tmp
/dev/vg00/lvol6 1704377 1119313 414626 73% /opt
/dev/vg00/lvol5 151509 2497 133861 2% /home

And if I do:

lvdisplay -v /dev/vg00/lvol1 |more

--- Logical volumes ---
LV Name /dev/vg00/lvol1
VG Name /dev/vg00
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 48
Current LE 12
Allocated PE 24
Stripes 0
Stripe Size (Kbytes) 0
Bad block off
Allocation strict/contiguous
IO Timeout (Seconds) default

And I don't understand one thing why I have less space??

/dev/vg00/lvol1 47829 18749 24297 44% /stand

LV Size (Mbytes) 48

And its the same for the others lvols, I have assigned 48MB (for exemple), but really I have less. Why?? The version is HP-UX 10.20, maybe I could solucion it with some patche??

Thanks a lot of!
Carmen.

Re: Space in lvol

Keely Jackson — Fri, 27 Sep 2002 12:26:32 GMT

Hi

So far as I can see you have the correct amount of space. The bdf for lvol1 shows 47829Kb which is approx 48Mb. As I understand it, the files system reserves apporx 10% of the space as a reserve for itself. Therefore there will be a slight discrpancy between what you assign and what you have available.

Cheers
Keely

ps if you extend the logical volume, don't forget you must extend the file system after.

Re: Space in lvol

Yogeeraj_1 — Fri, 27 Sep 2002 12:27:29 GMT

hi carmen,

This is just a minor overhead.

48x1024=49512

thus only about 1 MB "wasted"

on my system, it is as follows:
==============================
SLX2:> lvdisplay -v /dev/vg00/lvol1 |more
--- Logical volumes ---
LV Name /dev/vg00/lvol1
VG Name /dev/vg00
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 300
Current LE 75
Allocated PE 150
Stripes 0
Stripe Size (Kbytes) 0
Bad block off
Allocation strict/contiguous
IO Timeout (Seconds) default

--- Distribution of logical volume ---
PV Name LE on PV PE on PV
/dev/dsk/c1t2d0 75 75
/dev/dsk/c2t0d0 75 75

--- Logical extents ---
SLX2:>bdf /stand
Filesystem kbytes used avail %used Mounted on
/dev/vg00/lvol1 295024 53672 211848 20% /stand
SLX2:>

===============================

Hope this helps!
Regards
Yogeeraj

Re: Space in lvol

Tom Geudens — Fri, 27 Sep 2002 12:30:17 GMT

Hi Carmen,
I agree with the above answer. You "see" exactly the space you've allocated. Do note however that you've mirrored the lvols (which is good practive by the way :-) :
Mirror copies 1 <--
LV Size (Mbytes) 48 <--
Current LE 12 <--
Allocated PE 24 <--
So in order to get your 48Mb you'll actually need twice as much physical space.

Is this what you are confused about ?
Tom

Re: Space in lvol

Helen French — Fri, 27 Sep 2002 12:35:19 GMT

Both of your outputs are correct. But remember that when you create a LV and a file system on it, you cannot use the entire space for storing data! You should have some space reserved for the FS details, tracking and file status. These data varies with FS version, type and space. Examples are FS superblock, FS cylinder group, inodes etc. When you store data/files in the FS, it keep tracks of all those information in these reserved spaces. So you will not get *ALL* FS space as FREE!

Now with the commands - lvdisplay will show you the LV details and it's right that you have given 48MB for the LV. But 'bdf' will not report the LV details! It will report only the amount of free space available on the File system. So the output of bdf also right! For more information, read this:
# man bdf