The largest dump device is too small

Posted on 2014-01-13
Last Modified: 2014-01-22
I am getting error about dmpchk_toosmall E87EF1BE.

Probable Causes
Neither dump device is large enough to accommodate a system dump at this time.

        Recommended Actions
        Increase the size of one or both dump devices.

Detail Data
Largest dump device
Largest dump device size in kb
Current estimated dump size in kb

In this case if I need to increase dump device size, what is the proper procedure to dump device size in mirrored rootvg.

Question by:sams20
  • 6
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LVL 68

Expert Comment

ID: 39777261

(1) Determine your dump devices:

sysdumpdev -l

You might see something like this:
primary              /dev/lgdumplv
secondary            /dev/sysdumpnull
copy directory       /var/adm/ras
forced copy flag     TRUE
always allow dump    FALSE
dump compression     ON

Open in new window

sysdumpnull is a dummy device, I only assume it as the secondary device.
If the secondary device is a real device use the name you found with the command given above to repeat all the commands given below (except (3)) for that device!

(2) Check the device sizes

lslv lgdumplv

Take the value shown next to "LPs" on the left and multiply it with the value next to "PP Size" on the right to get the device size in MB. Note the value for "PP Size". You will neeed it in (5) below.

(3) Check the size required to accommodate a dump:

sysdumpdev -e | awk '{printf "%.0f\n", $NF /1024/1024}'

This will show the estimated dump size in MB.

(4) Compute the difference between the values obtained in (2) and (3).

(5) Divide the value found in (4) by the "PP Size" found in (2). Round up to the next integer. This is the number of required additional partitions. I'll call it "nn" below.

(6) Increase the size of the device(s)

extendlv lgdumplv nn

That's all. The change will take effect on both sides of the mirror, and there is no background process which must be restarted.

(Optional) Check for success:

/usr/lib/ras/dumpcheck -p

If you don't get any output everything is fine now.

Author Comment

ID: 39777401
I got,

# sysdumpdev -l
primary              /dev/lgdumplv
secondary            /dev/sysdumpnull
copy directory       /xxxx_dump
forced copy flag     FALSE
always allow dump    TRUE
dump compression     ON
type of dump         traditional

#lslv lgdumplv
PP SIZE:        256 megabyte(s)

LPs: 21

21LPs size: 5376MB

PPs: 42.

I don't know which one should be correct,

# sysdumpdev -e | awk '{printf"%.of\n",$NF /1024/1024}'
# sysdumpdev -e | awk '{print "%.of\n",$NF /1024/1024}'
LVL 68

Expert Comment

ID: 39777425
sysdumpdev -e | awk '{printf "%.0f\n", $NF /1024/1024}'

"0" in "%.0f\n" is the digit  zero, not the letter "o".
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Author Comment

ID: 39777481
from, sysdumpdev -e | awk '{printf "%.0f\n", $NF /1024/1024}'
I got 5633 MB

4) Difference, 257MB

5) Devided by PPs ---> 6.1
Then here, nn = 6.1
LVL 68

Accepted Solution

woolmilkporc earned 500 total points
ID: 39777504
You must divide by "PP Size", as I wrote in (5), not by "PPs".

257  divided by 256 rounded up to the next integer gives 2.

So "nn" is "2" and the command to extend the dump device is

extendlv lgdumplv 2

We're almost there ...

Author Comment

ID: 39777566
Now I understand, but I have a question here, if I extend lgdumplv on one hdisk, what abaout another hdisk. It looks like mirrored rootvg, there are two hdisks in the rootvg.
# lsvg -p rootvg
hdisk0            active            536         396        
hdisk1            active            536         396
LVL 68

Expert Comment

ID: 39777574
Dump devices are generally not mirrored.

Check with

lslv -l lgdumplv

Do you see both disks?

If so (which I doubt) there is no reason to get worried nonetheless. Changing an LV always takes effect on both sides of the mirror.

Author Comment

ID: 39779243
With this command, "lslv -l lgdumplv" I got both hdisks.
LVL 68

Expert Comment

ID: 39779372
So your dump device is mirrored which is quite uncommon, indeed.

So run

extendlv lgdumplv 2

and the dump LV will be extended by 2 LPs (logical partitions) which means that both copies of the LV will be extended by 2 PPs (physical partitions) each.

lsvg -p rootvg will then show

hdisk0            active            536         394        
hdisk1            active            536         394

Don't worry, LVM will take care of all this, there is no other command required than just extendlv.

Author Comment

ID: 39783129
If I extend lgdumplv with more than 2PPs like 3 or 4 PPs, will it work.
LVL 68

Expert Comment

ID: 39783252
Yes, why not? There is sufficient space in rootvg anyway.

Do you want to make provisions for future growth of your crash dumps?

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