Can i create more than 80 VGs means VG81, VG82.....etc.?

[Bunty...]

# ll /dev/vg*/group | awk '{print}'
crw-r----- 1 root sys 64 0x000000 Apr 21 2005 /dev/vg00/group
crw-r--r-- 1 root sys 64 0x040000 Sep 15 14:58 /dev/vg04/group
crw-r--r-- 1 root sys 64 0x050000 Aug 14 07:04 /dev/vg05/group
crw-r--r-- 1 root sys 64 0x060000 Aug 14 07:12 /dev/vg06/group
crw-r--r-- 1 root sys 64 0x070000 Aug 14 07:24 /dev/vg07/group
crw-r--r-- 1 root sys 64 0x080000 Aug 14 07:34 /dev/vg08/group
crw-r--r-- 1 root sys 64 0x090000 Aug 14 07:55 /dev/vg09/group
crw-r--r-- 1 root sys 64 0x100000 Jul 10 00:46 /dev/vg10/group
crw-r--r-- 1 root sys 64 0x110000 Aug 14 08:04 /dev/vg11/group
crw-r--r-- 1 root sys 64 0x120000 Jul 10 00:46 /dev/vg12/group
crw-r--r-- 1 root sys 64 0x130000 Jul 10 00:46 /dev/vg13/group
crw-r--r-- 1 root sys 64 0x140000 Jul 10 00:46 /dev/vg14/group
crw-r--r-- 1 root sys 64 0x150000 Jul 10 00:46 /dev/vg15/group
crw-r--r-- 1 root sys 64 0x160000 Jul 10 00:46 /dev/vg16/group
crw-r--r-- 1 root sys 64 0x170000 Jul 10 00:46 /dev/vg17/group
crw-r--r-- 1 root sys 64 0x180000 Jul 10 00:46 /dev/vg18/group
crw-r--r-- 1 root sys 64 0x190000 Jul 10 00:46 /dev/vg19/group
crw-r--r-- 1 root sys 64 0x200000 Jul 10 00:46 /dev/vg20/group
crw-r--r-- 1 root sys 64 0x210000 Jul 10 00:46 /dev/vg21/group
crw-r--r-- 1 root sys 64 0x220000 Jul 10 00:46 /dev/vg22/group
crw-r--r-- 1 root sys 64 0x230000 Jun 28 13:33 /dev/vg23/group
crw-r--r-- 1 root sys 64 0x240000 Aug 29 11:08 /dev/vg24/group
crw-r--r-- 1 root sys 64 0x250000 Aug 29 12:37 /dev/vg25/group
crw-r--r-- 1 root sys 64 0x260000 Aug 29 13:36 /dev/vg26/group
crw-r--r-- 1 root sys 64 0x270000 Aug 15 16:26 /dev/vg27/group
crw-r--r-- 1 root sys 64 0x280000 Aug 23 15:18 /dev/vg28/group
crw-r--r-- 1 root sys 64 0x290000 Aug 17 16:05 /dev/vg29/group
crw-r--r-- 1 root sys 64 0x300000 Aug 17 16:58 /dev/vg30/group
crw-r--r-- 1 root sys 64 0x310000 Aug 11 10:59 /dev/vg31/group
crw-r--r-- 1 root sys 64 0x320000 Aug 12 17:10 /dev/vg32/group
crw-r--r-- 1 root sys 64 0x330000 Aug 11 14:17 /dev/vg33/group
crw-r--r-- 1 root sys 64 0x340000 Aug 17 17:28 /dev/vg34/group
crw-r--r-- 1 root sys 64 0x350000 Aug 18 12:13 /dev/vg35/group
crw-r--r-- 1 root sys 64 0x360000 Aug 18 12:19 /dev/vg36/group
crw-r--r-- 1 root sys 64 0x370000 Aug 18 12:19 /dev/vg37/group
crw-r--r-- 1 root sys 64 0x380000 Aug 22 14:57 /dev/vg38/group
crw-r--r-- 1 root sys 64 0x390000 Aug 22 15:03 /dev/vg39/group
crw-r--r-- 1 root sys 64 0x400000 Aug 22 15:05 /dev/vg40/group
crw-r--r-- 1 root sys 64 0x410000 Aug 22 15:08 /dev/vg41/group
crw-r--r-- 1 root sys 64 0x420000 Aug 22 16:23 /dev/vg42/group
crw-r--r-- 1 root sys 64 0x430000 Sep 2 11:36 /dev/vg43/group
crw-r--r-- 1 root sys 64 0x440000 Sep 8 14:10 /dev/vg44/group
crw-r--r-- 1 root sys 64 0x450000 Sep 8 15:28 /dev/vg45/group
crw-r--r-- 1 root sys 64 0x460000 Sep 8 16:53 /dev/vg46/group
crw-r--r-- 1 root sys 64 0x470000 Sep 8 17:21 /dev/vg47/group
crw-r--r-- 1 root sys 64 0x480000 Sep 14 14:39 /dev/vg48/group
crw-r--r-- 1 root sys 64 0x490000 Sep 14 16:16 /dev/vg49/group
crw-r--r-- 1 root sys 64 0x3a0000 Sep 30 10:37 /dev/vg58/group
crw-r--r-- 1 root sys 64 0x3b0000 Oct 4 13:39 /dev/vg59/group
crw-r--r-- 1 root sys 64 0x3c0000 Oct 4 13:39 /dev/vg60/group
crw-r--r-- 1 root sys 64 0x3d0000 Oct 4 13:39 /dev/vg61/group
crw-r--r-- 1 root sys 64 0x3e0000 Oct 4 13:40 /dev/vg62/group
crw-r--r-- 1 root sys 64 0x3f0000 Oct 4 13:40 /dev/vg63/group
crw-r--r-- 1 root sys 64 0x1f0000 Oct 4 13:40 /dev/vg64/group
crw-r--r-- 1 root sys 64 0x2a0000 Oct 4 13:40 /dev/vg65/group
crw-r--r-- 1 root sys 64 0x1a0000 Oct 3 14:07 /dev/vg66/group
crw-r--r-- 1 root sys 64 0x1b0000 Oct 6 13:19 /dev/vg67/group
crw-r--r-- 1 root sys 64 0x1c0000 Oct 6 13:19 /dev/vg68/group
crw-r--r-- 1 root sys 64 0x1d0000 Oct 6 13:19 /dev/vg69/group
crw-r--r-- 1 root sys 64 0x1e0000 Oct 6 13:19 /dev/vg70/group
crw-r--r-- 1 root sys 64 0x2b0000 Oct 18 15:58 /dev/vg71/group
crw-r--r-- 1 root sys 64 0x2c0000 Nov 16 05:20 /dev/vg72/group
crw-r--r-- 1 root sys 64 0x2e0000 Dec 2 11:54 /dev/vg74/group
crw-r--r-- 1 root sys 64 0x2f0000 Dec 7 15:34 /dev/vg75/group
crw-r--r-- 1 root sys 64 0x2d0000 Dec 9 11:13 /dev/vg76/group



1. Can i create more than 80 VGs means VG81, VG82.....etc.?
2. what will be the next value in hexa of 0x2f0000 for more new VGs.

[Patrick Wallek]

What is your maxvgs kernel parameter set to? That value is the max number of VGs you can have on your system.

It looks like you have lots of room left in your minor number sequences. I see:

0x0a0000
0x0b0000
0x0c0000
0x0d0000
0x0e0000
0x0f0000

are not currently used. You could potentially use any of those.

[A. Clay Stephenson]

1) The limit is determined by the kernel tunable, maxvgs, which can go up to a maximum value of 256. You need to check your current setting and possibly increase it and build a new kernel.

2) You must have missed the class on hexadecimal arithmatic. Your next minor number would be 0x300000, 0x310000, ... 0x3f0000.

[Chan 007]

Hi,

All you need create txt file with minor numbers VG names, then use read to get minor number and VG so VG will be created ASAP..
Check your Kernal Parameted maxvgs...

kmtune -q maxvgs

cheers...007

[Deoncia Grayson_1]

If the maxvgs kernel parameter is set to a number higher then 80 then you can create more then 80 volume groups.

[James R. Ferguson]

Hi:

One other consideration in incrementing the kernel value of 'maxvgs' in order to accomodate a large number of volume groups may be of interest.

About 4-8 KB of lockable kernel memory is consumed for *each* increment in 'maxvgs'.

Regards!

...JRF...

[Bunty...]

---------------------------------------------------------------------------------------------------------------------------/\
Tunable Current Planned Dynamic Auto Tuning
Value Value
=============================================================================================================================
maxvgs 80 80 no


can i change this value to 100 or 256 or less than 256.
which value i should choose?


may i choose this series for new VGs--0x4a0000, 0x4b0000......

[James R. Ferguson · Accepted solution]

Hi (again):

In answer to your last question, '0xff' or 255 decimal is the limit, since the device file minor number encodes this. Choose something reasonable that meets your needs but gives a little room for growth.

Regards!

...JRF...

[Patrick Wallek]

How many more VGs are you going to need in the future? I wouldn't set it any higher than necessary. I definitely wouldn't set it to 256. I would be tempted to do 90 or 100.

Also, yes you could go with 0x4a0000. It appears that those are not in use right now.

[Chan 007]

Hi,

Leave it as it as you see 90vgs so far.
I say you can keep it 256, even though you may not use it, it doesn't harm your system...

007

[Bill Hassell]

Do you really need hundreds of volume groups? A volume group can contain multiple disks, not just one. For filesystems, the maximum for a single mountpoint is one volume group with one lvol. From a sysadmin point of view, a very large number of volumes can be difficult to manage.

[Geoff Wild]

VG80 should have a minor number of 0x4f0000 - though not completely neccessary - but 50 Hex = 80 decimal.

maxvgs sets the upper limmit of the minor number - example:

If you create a vg79 and try to make the minor number 0x790000 - it won't work if your maxvgs is 80 - why? because 79 HEX is 121 decimal - which is 42 vg's more then you can have with MAXVGS at 80 (starts with vg00).

PS: ll /dev/vg*/group | awk '{print}'

is the same as ll /dev/vg*/group

you don't need the awk in this case...

Rgds...Geoff