LVM and VxVM

several logical volumes/several volume groups

 
CSP_ALGERIA
Frequent Advisor

several logical volumes/several volume groups

Hello,

In HP-UX 11i, with oracle using different mount point, is better to create one VG with several logical volumes? Or create several volume groups with one or logical volume?

So in witch configuration HP-UX work fine and what is the impact for the performance???

Best regards

Omar
s
Nothing in the world can take the place of persistence.
7 REPLIES 7
Peter Godron
Honored Contributor

Re: several logical volumes/several volume groups

Omar,
if you thinking about the suggestion to have different parts of the oracle database in different locations, it is the physical location that impacts.
The I/O to the disk is the potential bottleneck.
So split your DB across different disks/controllers, rather than different mountpoints on the same physical disk.
Rajeev  Shukla
Honored Contributor

Re: several logical volumes/several volume groups

The feactures of LVM are best used when you have less VG and create all LV in them. This gives you flexibility in resizing the LV, extending them etc..
Also there is a parameter in kernel MAX VG, after a while you will run out and need to increase this parameter if you choose to have more VG
Abhijit P.
Valued Contributor

Re: several logical volumes/several volume groups

Hi..

In a LVM enviornment it is always better to have less VGs and corresponding filesystems in that VGs ( i.e. LVs) this is reduce the complexity of the file systems and even the I/O operation among the file systems.

Regards,
Abhijit
Devender Khatana
Honored Contributor

Re: several logical volumes/several volume groups

Hi,

There should not be any impact on performance because of no. of VGs in system or no. of LVOLs in each VG. Moreover a better impact will be due to the layout of the file systems i.e. stripping , mirroring etc.

I would suggest to have more than one VG to differentiate the type of LVOLs. One for redologs, one for data files and one other for other data.

HTH,
Devender
Impossible itself mentions "I m possible"
Tiziano Contorno _
Valued Contributor

Re: several logical volumes/several volume groups

I second Devender reply and I suggest you to also consider to create as many VGs as pairs, where destination is datafiles, indexes, redo.

Each VG can have different set of disks, more or less performant and help you administer and have a glance with a bdf :)

This VG separation also considering Service Guard packages switches: packages bring with them entires VGs, so their LV: you have to setup different sets of VG for each instance you want to be able to run separately.

Regards.
Pat Obrien_1
Regular Advisor

Re: several logical volumes/several volume groups

In my experience the numbers of vg and lvm don't matter for perf reason if the db is laid down right. What does matter is the flexibility you may need later on. LVm allows to to export and vg and import to another system withthe caveat that all logical volumes in the vg must go as a set. In my environment I am always loading the db with new stuff, so I will be told by the dba which volumes will need to be exported and then imported to a prep box where the files will come out of another process and then I will reverse the process and tel them when I am done. The dba will then sql load these into the db. This process works days faster on large loads the sql loading over nfs or ftp files locally.
I have 1 volume per vg to keep my flexibiltiy and I have hundreds of volumes. yess tha admin sucks but just doing what they ask for when it makes sense from previous foo bars.
Steve Blackburn_3
Occasional Advisor

Re: several logical volumes/several volume groups

Omar,

Whether one uses seperate VGs or 1 VG is a matter of preference. An additional performance tuning item to consider is mount options, e.g, direct i/o or fs cache. You should look at the type of disks whether, e.g. MSA drives compared to symm, and if your multipathing.