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Storage Foundation concept

Created: 21 Aug 2009 • Updated: 21 May 2010 | 3 comments

Hello

Colleagues, I've qestion about concept how to organize Storage Groups.
Situation look like - EMC storage gives luns for SFORA for Oracle RAC 2 node cluster. VxVS manges 4 storage groups. In each Storage Groups is from 5 to 17 luns (~1TB each). Capacity volumens created on top of this SG is near full. My question is - what is the better solution create new SG
1.add new luns -> create volumens (for Oracle tablespaces) or
2.add new luns to exiting SG -> resize volumens -> resize vxfs? What are advantages and drawback this solutions?

Regards
Marek

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jimmybhathena's picture

Hi Marek

First of all could you please clarify about the Storage Groups? Are we talking about diskgroups? The terms volumens is it something to do with Netbackup or are we talking about VxVM Volumes?

Jimmy Bhathena

marek.dabrowski's picture

Hi

My mystake - Storage Groups I mean Disk Group. Volumens are VxVM volumens.

Regards

Gaurav Sangamnerkar's picture

Hello Marek,

so if I understand correctly, you have 4 Veritas diskgroups,  each diskgroup has 4-17 Luns of ~1TB each (so lets take max 17TB), You have created verias volumes & filesystems over it, & now these filesystems are approx full, now you would like to know which is better solution:

a) Create new diskgroup & add new luns here
b) Add new luns to existing diskgroups & resize volume & FS.

I hope my understanding is correct... if yes then see my answers below....

So lets consider both:

a) Create new diskgroup:-   In this case, VXVM has no issues, would be a good choice to add new diskgroup as you will get new area for private region. There is a probability if there are too many objects (subdisks, volumes, plexes), private region config copy space would be utilized & there is no way in VXVM where you can resize length of private region without reinitializing. So creating new diskgroup would be a good idea however on the drawback side, it would increase administration work. If you are using a cluster (RAC/oracle as mentioned above), you will need to add new resource & put this new diskgroup into cluster configuration. Also linking of resources has to be done in correct fashion, you also will need to create new volumes & new filesystems & new mount points here (at VXVM layer) & put them in cluster control.

b) Adding space to existing diskgroup:- In this case unlike above, there would be less administration task, since diskgroup & volumes would be already under cluster control, you don't need to create any extra/new resources, however resize operation will be there.

If your filesystems are 100% full, it is likely that resize operation might fail, you need to bring down usage of FS before resizing it...
You also need to see if enough private region space is available & there are not too many objects....

You can find this by using following command:

# vxdg list <diskgroup> | grep "config:"

for example:

 # vxdg list vrdg | grep "config:"
config:    seqno=0.1139 permlen=48144 free=48131 templen=7 loglen=7296

as you can see above, I have good amount of free space in private region.

I hope this answers your query....

Gaurav

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