Reasons to Use VxVM

[Duncan Edmonstone]

Just out of interest, what are the drivers to move to using VxVM(full product rather than the base) over LVM? These are the ones I know about myself...

Pros:
Dynamic Multi-Pathing (DMP)
Software RAID-5

Cons:
Root VG must still be LVM
Cluster Lock in MCSG must still be LVM

[melvyn burnard]

CONS:

cost? you need to pay for the full license
speed? I have so far seen VxVM be a lot slower than LVM
my personal opinion

[Bill McNAMARA_1]

a winNt ,sun and ibm system will be able to mount the vxvm devices. ie it's good for the san.

other than that don't bother.

Later,
Bill

[Sebastien Masson]

Right now? if you realy don't need the DMP and RAID 5 software, you don't need VxVM. Because you need to have a rootdg before any other disk group, and you can put the OS in VxVM. If you put your data in the rootdg and you lost it, you lost all your other disk group. Only HP-UX 11.20 (11i v1.5) support OS in VxVM but right now it's only release for Itanium but it's comming for PA-RISC.

VxVM is little bit slower then LVM because you have some much layer (disk group, volume, plex, sub disk, disk) instead of (vg, lv, pv).

But you have some nice feature like the online relayout (change from raid x to raid x online on change raid layout).

For the DMP, if you have an EMC storage (Symmetrix) PowerPath is better then DMP, DMP is round robbin. For EMC CLARiiON, pvlink is the only choice because a LUN can only be under one SP. Like many other HP storage system.

Me I have EMC storage, SAN N4000, some HP FC10, Model 30 and I run HP-UX 11i with LVM but I know HP go on VxVM and someday LVM will not be supported... but for now...

And in a day when you don't have the choice, HP will provide tool to convert (this tool already exist in Base VxVM) LVM to VxVM

[harry d brown jr]

Personally, unless I have to, I would not move to VxVM as there are no compelling reasons to do such. As Bill noted that they can become available for other OS's, but what guarntees do we have that Veritas will be able to have the same releases available to every OS?

Right now, I'm a fan of Veritas on SUN platforms, because the 70's thinking on how to slice disks is a major step backwards. Veritas allows you, on sun platforms to have a decent (but not perfect) lvm.

Do I need multipathing? Not really, because I already have at least two paths to every disk.

Do I need dynamic path load balancing? Not really, I'm not hammering my IO subsystems because I do a little more planning and purchasing.

Did you realize that purchasing Veritas for a SUN Netra is almost the same price as the hardware itself? I've told Veritas that they are insane if they think I'm going to purchase 40 licenses at that price.

If HP tries to cram veritas down my throat, I might think about AIX.

live free or die
harry

[Roger Baptiste]

hi,

Last month there was a long thread about lvm versus vxvm, where the overwhelming response was for keeping the LVM boat alive, even though Vxvm has some benefits like DMP, supposed flexibility in configuration options.

If you are intrested in using vxvm , i would suggest you try it on a solaris box and then make your decision.

-raj

[Duncan Edmonstone]

I *have* used VxVM in a Solaris environment, and although it is an improvement over the ridiculous standard Sun method of disk slices - my real big issue with it is it's lack of integration with the core OS - witness the painful act of doing a Solaris upgrade with a VxVM encapsulated root disk (direct quote from Sun support engineer: 'oh dear - you didn't do it as described in the manual did you?').

If HP can make me feel comfortable about:
- Tight Core OS integration (I hope I'll be able to do the equivalent of 'hpux -lm')
- Licensing Costs vs. LVM
- Upgrade paths including conversion tools
- HP education (I still can't go on a HP VxVM course here in the UK! Veritas courses are always on NT or Solaris)

Then with a tear in either eye I will be able to let go of LVM! And as Harry says - if I don't like it I can always become an AIX Admin!(or Linux now LVM & ServiceGuard are ported)

Cheers All

Duncan

[Manish Bharadwaj]

As most of you have indicated above if HP donot force us to go for veritas I will always prefer lvm.

I was shocked to realise that HP was not able to boot its operating system with lvm (on HPUX 11i ver 1.5) and forced to use veritas.

I am also working on sun systems were we donot have more choice other than using veritas .
I personally feel that lvm is much much better their veritas if you donot use additional veritas function like DMP,raid 5 etc.

But to me it looks like sooner or latter HP will stop supporting lvm and we will be forced to use veritas.

[Michael Tully]

Hi,

I cannot see any other advantages other than
what has been mentioned, except of course
for using a GUI front-end to basically use
an LVM look-alike....
Sun boxes... well they needed something other
than that was created in 1970 something.....
Other thing about vxvm is the install is a
pain in the .... as it requires about 100
different patch combinations....

My 2 cents worth

-Michael

[Eric Buckner]

A little late into this conversation, but I really have to add some plusses to Veritas on a few things that you guys tend to be over looking. I have been running VxVM on everything but vg00 for the past 7 months and I have to tell you I love it over LVM.

LVM in a SAN environment is archaic to say the least. You get a primary and alternate path to a device and that is it. With VxVM I have 6 paths to the same device and w/ DMP I balance my load across all of those paths instead of just using the primary path until failure. Sure you can create your vg alternating between primary and alternate, but that gets cumbersome and it still doesn't afford you the load balancing that DMP gives you.

Second you can stripe across controllers. The closest you get to striping w/ LVM is PP striping or what I affectionately call "Chunky Striping". Granted I am hooked to an XP512 and as such I am not concerned about using RAID 0/1 or RAID 5 but stripping data across controllers really improves performance.

As far as the GUI goes, I don't like it. I usually just do everything from the command line. The GUI is OK but they need to have a bit better documentation inside the GUI on how to do what you just did via the command line. All in all I think VxVM is a very robust VM and I don't think it has gotten a fair shake from the HP LVM dead-enders. True it doesn't have Core OS integration, give it time. I can honestly say I have been extremely happy w/ VxVM in managing our 6 TB of disks (and 12 TB by end of year). There is no way I would want to do this w/ LVM.

Eric