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AIX : hd1 shows 100% usage only /home mapped to it

Posted on 2008-11-17
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Last Modified: 2013-11-17
Hello experts
On our application server when I run topas HD1 shows 100 % usage. Only /home is mapped to it as I can see by running the lsvg -l rootvg command.
Please help
regards
Atap

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Question by:aojha
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Expert Comment

by:dfke
ID: 22982687
Use du -k /home to see what's filling it up and see if you can clean something up.
Or check the amount of free PP's on rootvg with lslv rootvg and increase /home:

smit jfs --> Change / Show Characteristics of a Journaled File System
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Accepted Solution

by:
woolmilkporc earned 1000 total points
ID: 22982747
Hi,
I assume you mean the I/O load of HD1 ist 100%, and not space occupation?
But how can you see HD1 in topas? Do you mean hdisk1?
Anyway, if it's hd1 (/home) you could use 'fuser /dev/hd1' to see all the pids accessing it.
From manpage -
Each process number is followed by a letter indicating how the process uses the file:
       c            Uses the file as the current directory.
       e            Uses the file as a program's executable object.
       r            Uses the file as the root directory.
       s            Uses the file as a shared library (or other loadable object).
 You should examine all the processes to find out which one could be causing the I/O load.
 
If it's hdisk1 instead, the most probable cause of high I/O load is paging.
Examine the corresponding sections in topas (PAGING, MEMORY, PAGING SPACE) to find out what could be going on.
 
A better way to do this might be using nmon. Find it here-
 
http://www.ibm.com/developerworks/wikis/display/WikiPtype/nmon
 
I'd appreciate if you would clarify your problem a bit.
 
wmp
 
 
 
 
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Author Comment

by:aojha
ID: 22983121
Hi wmp,
You are spot on. I was talking about hdisk1. I am an app person not an admin so please forgive my ignorance.
I just generated a report from nmon and it seems that /t24 mount point which is the application mountpoint is only mapped to phsysical device hsdisk1. There are many application instance running here which are  hammering hdisk1 which causes the usage to go at 100%.
hdisk0:
LV NAME               LPs     PPs     DISTRIBUTION          MOUNT POINT
hd8                   1       1       00..00..01..00..00    N/A
hd4                   8       8       00..00..08..00..00    /
hd2                   24      24      00..00..24..00..00    /usr
hd9var                1       1       00..00..01..00..00    /var
hd5                   1       1       01..00..00..00..00    N/A
hd6                   2       2       00..02..00..00..00    N/A
hd3                   8       8       00..00..08..00..00    /tmp
hd1                   1       1       00..00..01..00..00    /home
hd10opt               12      12      00..00..12..00..00    /opt
fslv02                20      20      00..20..00..00..00    /imtf
fslv01                40      40      00..40..00..00..00    /swtmp
lg_dumplv             8       8       00..08..00..00..00    N/A
hdisk1:
LV NAME               LPs     PPs     DISTRIBUTION          MOUNT POINT
hd8                   1       1       00..00..01..00..00    N/A
hd4                   8       8       00..00..04..00..04    /
hd2                   24      24      00..00..24..00..00    /usr
hd9var                1       1       00..00..01..00..00    /var
hd5                   1       1       01..00..00..00..00    N/A
hd6                   2       2       00..02..00..00..00    N/A
hd3                   8       8       00..00..08..00..00    /tmp
hd1                   1       1       00..00..01..00..00    /home
hd10opt               12      12      00..00..12..00..00    /opt
fslv00                480     480     109..107..58..109..97 /t24
hdisk0          00c739e22258cb96                    rootvg          active
hdisk1          00c739e2222bf6b9                    rootvg          active

Is there any easy way to split /t24 across hdisk1 and hdisk0 so that both physical harddisk show activity ?
Thanks
Atap
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Expert Comment

by:woolmilkporc
ID: 22983243
Hi,
yes, you can split it, but it's not _that_ easy.
How about mirroring?
Given you had enough freespace on hdisk0 and given /t24 had much more Read I/O than Write I/O, mirroring would be a solution.
If you are not sure about freespace, please post the output of 'lsvg-p rootvg' and 'lsvg rootvg'.
Regarding the split, I will think about a good strategy ...
 
wmp
 
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Assisted Solution

by:sjm_ee
sjm_ee earned 1000 total points
ID: 22983333
Looks like you have an AIX system with just two internal disks (hdisk0, hdisk1) and the application data in /t24 in rootvg. Further it looks like the standard logical volumes of rootvg are mirrored across hdisk0 and hdisk1. You can tell by looking at the output of "lsvg -l rootvg" and seeing that the number of physical partitions (PPs) for hd1/2/3/4/5/6/8/9var/10opt are double the number of logical partitions (LPs).

Now /t24, /imtf and /swtmp are unmirrored. First thing to check is how much disk space you have left - use "lspv hdisk0"  and look for "FREE PPs". If you have >=480 free PPs then you could mirror /t24 - that would not only protect the data against disk failure but also allow AIX to split read i/o across the two disks. In order to do that, first check the  "SCHED POLICY" of the LV is "parallel" using "lslv fslv00". Then use "smit mklvcopy" to change the number of copies to 2 and specify hdisk0 as the disk to add partitions on. and synchronise now - make sure to do this out of prime time.

The other way to split the i/o without buying new hardware is to backup the data, delete the filesystem and recreate it on a striped LV across the two drives. This will not protect the data against a disk failure but will even up the i/o. However in you situation, where it was the original intention to mirror the data, I would not recommend this.
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Author Comment

by:aojha
ID: 22984096
hi guys,
output from the lspv comands for oth hdisk1 and hdisk2. seems like I will have to free some space on hdisk0 to have around 500 PPS free and then mirror /t24 app directory. Can you please advise me on how to go about it. Apologies I am not an AIX expert so am asking basic questions.
# lspv hdisk0
PHYSICAL VOLUME:    hdisk0                   VOLUME GROUP:     rootvg
PV IDENTIFIER:      00c739e22258cb96 VG IDENTIFIER     00c739e200004c000000011c2258cc13
PV STATE:           active
STALE PARTITIONS:   0                        ALLOCATABLE:      yes
PP SIZE:            256 megabyte(s)          LOGICAL VOLUMES:  12
TOTAL PPs:          546 (139776 megabytes)   VG DESCRIPTORS:   2
FREE PPs:           420 (107520 megabytes)   HOT SPARE:        no
USED PPs:           126 (32256 megabytes)    MAX REQUEST:      1 megabyte
FREE DISTRIBUTION:  109..39..54..109..109
USED DISTRIBUTION:  01..70..55..00..00
# lspv hdisk1
PHYSICAL VOLUME:    hdisk1                   VOLUME GROUP:     rootvg
PV IDENTIFIER:      00c739e2222bf6b9 VG IDENTIFIER     00c739e200004c000000011c2258cc13
PV STATE:           active
STALE PARTITIONS:   0                        ALLOCATABLE:      yes
PP SIZE:            256 megabyte(s)          LOGICAL VOLUMES:  10
TOTAL PPs:          546 (139776 megabytes)   VG DESCRIPTORS:   1
FREE PPs:           8 (2048 megabytes)       HOT SPARE:        no
USED PPs:           538 (137728 megabytes)   MAX REQUEST:      1 megabyte
FREE DISTRIBUTION:  00..00..00..00..08
USED DISTRIBUTION:  110..109..109..109..101
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