hard disk size in service guard

[Samudrala Seshpani]

Hi,

Currently with the available plvol volumes; I notice my application will run out of space in coming few weeks(most of the volumes are above 85%). In this regards I need some guidance.

The total plvol is coming to 40G as of now in bdf. Our system is with 6X36GB(104 Gb usable on raid 1).
In that case there must be more harddisk space available to configure(correct me). So how to add more plvol or increase existing plvol. Need detailed steps as I am more into SAP basis admin and only require to provide HP-UX support to the minimum admin level. So I do not have hands on experience on these matters.
OS is HP-UX 11.0(64) with SG/MC.
+ Oracle 8.1.7(64)
Thanks in advance
Sesh

[Sunil Sharma_1 · Accepted solution]

Hi,

please attach o/p of these commands.

#ioscan -funC disk
#strings /etc/lvmtab
#vgdisplay -v vg*
#bdf


Sunil

[Samudrala Seshpani]

Hi Sunil,

As requested I have attached the info.

Thanks for your quick reply.

Regards

Sesh

[Samudrala Seshpani]

Sorry, I missed the bdf output. Pl see the attachment.

Thanks
Sesh

[Samudrala Seshpani]

Hi,

Can someone help me on this please...

Thanks
Sesh

[Samudrala Seshpani]

Included vgdisplay -v /dev/pvg* output which was missing in previous attachement

Thanks
Sesh

[Rajeev Shukla]

Hi Sesh,
I posted the solution in your other post
Hi Sesh,
If you have a look at the output of vgdisplay you will find (say lets take VG00)
Total PE 8680
Alloc PE 6445
Free PE 2235
Which says that the total physical extents are 8680 and since the
PE Size (Mbytes) 8
so you have total 8680*8=69.44GB in VG00, allocated is 6445*8=51.560GB, free is 2235*8=17.88GB the same way you can do for other VG. Now to look which disk has free space look at the end of the vgdisplay where you see the physical volumes belonging to that disk(say first disk in VG00)
PV Name /dev/dsk/c1t2d0
PV Status available
Total PE 4340
Free PE 1030
free space =1030*8=8240MB
and other disk has free space 1205*8=9640MB
Thats how you can see whats the space available in a VG and which disk has more free space, that will help you in adding a LV to that VG and extend it to the disk which has required space.

[Samudrala Seshpani]

Hi Rajeev Shukla ,

Thanks for your info.
Now I am able to identify the free space on my disk. The issue is being for related to my oracle data disk which in this case is pvg80, I have calculated the space as follows (correct me please)
There are two disks and in each disk there is appro 14 GB free.
Now my question specific to pvg80:

There are 6 logical volumes for my data filesystems.
1. Is it possible to increase the size of these file system (ie logical volume)?
2. What is the best practice? Increasing current size of logical volue or adding new logical volume?
3. As there is altogether appro 28GB free would it be OK if I add another logical volume of say 5 GB to pvg80?
4. Can a sys admin use entire disk space while allocating or he should leave some portion as buffer? If so how much would be recommended to have as buffer?
5. In service guard could you please help me how to follow this process so that the other node also know about the changes and so will help during cluster takeover.

Thanks once again

Sesh

[Rajeev Shukla]

Hi Sesh,
Can you first confirm me one thing, are LV's in pvg80 mirrored, becuase when i look at the LV's in that VG i see all say 2 PV used, which can mean that the LV is mirrored on both PV to find that out more clearly do lvdisplay -v /dev/pvg80/plvol81 if you see something like this
LE PV1 PE1 Status 1 PV2 PE2 Status 2
00000 /dev/dsk/c1t2d0 00000 current /dev/dsk/c2t2d0 00000 current
00001 /dev/dsk/c1t2d0 00001 current /dev/dsk/c2t2d0 00001 current
00002 /dev/dsk/c1t2d0 00002 current /dev/dsk/c2t2d0 00002 current

it means they are mirrored. Now answers to your questions.
1. Yes you can extend the present LV to 1805*4=7220MB
2.You can even add another LV and if you dont want that mirrored then you can create upto 2*1805*4=14.44GB
BEAR IN MIND THAT THIS VG HAS
PE Size (Mbytes) 4
THAT IS WHY ALL ARE MULTIPLIED BY 4 NOT 8
3. looking at the space you can either add a new LV mirroed upto 7GB or create a unmirrored LV upto 14GB or extend a present LV upto 7GB if it is mirrored.
4. Yes a sys admin can use entire space on the disk to create a LV or VG, there is no need of any buffer space, as the filesystem takes care of it. When you create a filesystem on the LV the system allocates a buffer space from that LV (10%) and leaves the rest of the space for usage.
5. If you are increasing a filesystem then you need not worry of making the changes on the nodes in MCSG, but if you are adding a new LV to a VG then you need to export the volume group in shared mode with -p option i.e
vgexport -s -v -p -m pvg80.map pvg80
and import the same volume group on the other nodes in the cluster.
I hope i am clear in explaining your questions, if not let me know.

[Samudrala Seshpani]

Hi Rajeev Shukla,

Thanks for your quick replies.
Yes, they are mirrored. The output of the command lvdisplay is given here under to confirm the same.
So I only have 14GB space free in total. Further to go ahead with this knowledge I need your help to proceed.
1. What are the commands to increase the size of the existing filesystem say "/dev/pvg80/plvol84" to delta 4GB?
2. Which method do you sugget? Using command line or using SAM?
3. I am prefering increasing the filesystem(LV) size as it not require additional steps for node enabling. But need to double confirm with you about safety of the data on the filesystem(LV) due to this change. Would any mistake cause loss of data on the filesystem?
4.How to perform the mirror part enabled when the LV is increased.
5.Is there any limitation about having how much GB of space as LV.
6. Please give me the commands to follow if I decide to go for adding new LV(filesystem).

Your information is really helped me a lot to analyse the status of my disk.

Sorry to trouble you with more questions.

Thanks and regards

Sesh

Output of lvdisplay -v /dev/pvg80/plvol81>/tmp/lvd.txt
--- Logical volumes ---
LV Name /dev/pvg80/plvol81
VG Name /dev/pvg80
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 4096
Current LE 1024
Allocated PE 2048
Stripes 0
Stripe Size (Kbytes) 0
Bad block on
Allocation PVG-strict
IO Timeout (Seconds) default

--- Distribution of logical volume ---
PV Name LE on PV PE on PV
/dev/dsk/c4t2d0 1024 1024
/dev/dsk/c5t2d0 1024 1024

--- Logical extents ---
LE PV1 PE1 Status 1 PV2 PE2 Status 2
00000 /dev/dsk/c4t2d0 00000 current /dev/dsk/c5t2d0 00000 current
00001 /dev/dsk/c4t2d0 00001 current /dev/dsk/c5t2d0 00001 current
00002 /dev/dsk/c4t2d0 00002 current /dev/dsk/c5t2d0 00002 current
00003 /dev/dsk/c4t2d0 00003 current /dev/dsk/c5t2d0 00003 current
00004 /dev/dsk/c4t2d0 00004 current /dev/dsk/c5t2d0 00004 current
00005 /dev/dsk/c4t2d0 00005 current /dev/dsk/c5t2d0 00005 current

[Rajeev Shukla]

Hi Sesh,
Sorry for replying so late, i left office and am at home now(its too late here).
So as we analysed we have only 7GB (7GB primary and 7GB mirror=14GB) to play with.
1. To increase the LV by 4GB use
lvextend -L /dev/pvg80/plvol84
where =old size+4GB
unmount the filesystem and increase it
umount /oracle/PRD/sapdata1
extendfs -F vxfs /dev/pvg80/rplvol81 (care that we use rplvol81 not plvol81, character device file)
2. Its easy to do through and if you are not confident of comand line use SAM.
3. A change in LV doesn't require any updation on other node in the cluster, its only change in VG requires a updation on other node.
4. Dont worry about mirroring, if an LV is already mirrored and you increase it, the increased portion will also be mirrored.

Commands to create a new LV
lvcreate -m 1 -L -n /dev/pvg80
newfs -F vxfs /dev/pvg80/r
mkdir
mount /dev/pvg80/

[Samudrala Seshpani]

Hi Rajeev Shukla,

Excellent, U made things very easy for me. Hats off to you.

Your detailed steps would sure help me to perform this task with ease. As I have development and UAT servers, first I will test these command in those servers and then later perform on production.

BTW, which country are you working now? I am working in Singapore and basically from India. Nice to get replies from you.

Thanks once again

Regards
Sesh

[Rajeev Shukla]

Thanks you very much Sesh,
I am happy that my reply helped you.
I too am from India, but working in Sydney for past 3 years.

Regards
Rajeev