Use LVM or VxVM with large array/san based storage?

[Alzhy]

We've a mix of large arrays: EVA, StorageWorks and Hitachi (Sun StorEdge 9980, HDS9960 === HP XP512?). We were mainly a SUN shop before and very experienced with Veritas Volume Manager and its close affinity with Oracle (and NetBackup of course).

Our inclination is to go with Veritas so existing tools/scripts/headware are maintained. Since it is now becoming closely woven with HPUX 11i and now current with versions for AIX and Solaris. Also, most Oracle features for scalability, clusterring and RAS are pretty much dependent on Veritas products. We actually find VxVM easier to manage than LVM and has more features.

Any experiences, comaprisons, etc... please.

[Caesar_3]

Hello!

For my opinion it's good to go on the VxVM
if you use multiple platforms.
For today almost every known unix kind platform
have port of VxVM so for the feature it's
also good thing.

Caesar

[Trevor Roddam_1]

Nelson.

It is good to go with what you know; however,
it would be good not to encapsulate the boot disks with Veritas.
Recovering from a boot disk crash is very difficult.
I personnaly have used SUN and HP-UX with VxVM and can see the benifits but I still prefer LVM on HP-UX and VxVM on SUN. Personal pref.

As you have some large storage arrays that do the hot spare and mirroring etc behind the sceens, I wouldn't bother with the expence on HP-UX. This is due to the recovery complexities do not out weigh the benifits. Check out ignite UX.

Active/Active pathing then becomes the issue.
This is not achievable from LVM without extra SW specific to the storage array.
As for existing backups, you will need to check out the commands on UX as they are different from SUN. Mainly by name but some options too.

HP is/has released some good intergrations for EVA and XP arrays into DataProtector for split mirror backups etc, EMC and others work also. It might be worth a look for your site. The Oracle intergration to OmniBack II I found easier than NetBackup, but that is probably the devil you know. It didn't need any scripting as it was all included. You did need to set up Oracle though.

Hope this helps.
Trevor.

[Vincent Fleming]

What I've been seeing with my customers that use VxVM - both on Sun and on HP-UX - is that they use VxVM on Solaris because there's no other choice, but prefer LVM on HP-UX.

There are several reasons for this... LVM's path failover, PV-Links, is more reliable than DMP. I've often had customers complain that DMP didn't failover properly, and brought their systems down, but I've never heard a complaint about PV-Links.

As for Oracle integration - did you know that HP-UX is the development platform for Oracle now? It has been for several years. The Oracle folks have done a nice job integrating Oracle with HP-UX.

So, in a nutshell, it seems that a lot of people agree with you that VxVM is easier to setup and manage, but LVM seems to be more stable.

Good luck,

Vince

[Alzhy]

Well, we do not have plans of using encapsulation (using VxVM rootability) for the very reasons of simplicity. On Solaris environments, we use Diskuite to manage our boot/system disks and Veritas for all the rest. Until LVM is phased out - we will stick with LVM on managing our system VG with MirrorDisk/UX and Veritas for the rest.

Vincent, VxVM is used on Solaris environments specially on large environments (and using RDBMS's from Oracle specially.) It is not a matter of choice but standards.. Diskuite (now called Solaris Volume Manager) is a whole lot similar to LVM but still not close to Veritas Volume Manager in terms of features, performance, scalability and stability.

Among the storage software vendors, Veritas has the most seamless integration with Oracle (heard of ODM and QuickIO?). Veritas in its strategy of releasing the same versions on all platforms has proven yet again that it does not have any hardware agenda.

I thought I read some time ago about the future of LVM -- about it being phased out (the signs are here, VxVM now being part of HPUX and finally supporting rootability). Well in my opinion, it should not be as it has a niche in "small" server implementations. Besides, Linux has already adopted LVM (the free version) as its built-in volume manager and HPUX admins are pretty much at home on Linux machines with LVM as the volume manager.

[Duncan Edmonstone]

Nelson,

LVM *will not* be phased out - it looks like it will be integrated into the TruCluster technology that is coming from Tru64 into HPUX. My understading is that you will only be able to have an AdvFS clustered filesystem on an LVM volume (NOT VxVM).

Of course VxVM has its own clustered volume manager (and clustered file system) - but this currently has some fairly major issues (like you can only configure one heartbeat network between CVM nodes)

so don't expect LVM to go anywhere yet...

HTH

Duncan

[Vincent Fleming]

I think Duncan has a good point here... and let me add one more, which is my own opinion (not HP's)...

HP seems to have distanced itself from VxVM somewhat since it's inclusion in 11i, and I think this is because HP has MC/SG, TruCluster, and a host of other products (such as backup) that compete directly with Veritas' other software suites - and because of this competition on several fronts, the relationship between HP and Veritas is, and has been, strained somewhat. Oracle is as well integrated with LVM and other HP products (online backup, clustering, etc) as it is with Veritas.

I think that HP (and Oracle for that matter) wants to provide what customers are looking for... be that Veritas or not. Some people have a real problem with having to purchase a bunch of software from Veritas just to run their systems. Others (like you, I gather) find enough value-add from Veritas to go ahead and spend the extra money.

Personally, I really could not care less what customers do, as long as they are happy!

If you are very comfortable with Veritas, and it sounds like you are, then I think you should use it, and make your life easier. The reason I initially posted a reply was to point out that there have been problems with the DMP feature in the past, and you may want to consider alternatives, such as AutoPath, SecurePath, or PowerPath, depending on your disk array.

Good luck,

Vince

[Trevor Roddam_1]

Nelson.

I would have to concur with Vincent on this.
I had issues, that were never realy resolved with path failover and VxVM on Solaris (E10K).

I find it easier to recover lost disks using LVM alone, but it could be argued that this is a compfort issue more than technical.

Personnaly I wouldn't use it on HP-UX as I find that there is not a cost benifit.
The only thing that I would use VxVM for would be Hot Spare. Online JFS has a much better snapshot for single systems.

HP were going to use Veritas VM; however, have withdrawn from it as it could not be intergrated with MC/SG and was too dificult to get the boot disks right. Now with True64 comming on board and IA64, I don't see this as their way forward.

On SUN; however, I wouldn't be without it as the supplied system is not worth worrying about.

I would be concerned about support from HP if you did use VxVM with Oracle RAC. Too much complication.

My two cents anyway.

Trevor.

[Alzhy]

People complain about Veritas because of problems not directly related with its software products and the customers not really knowledgeable and experienced enough. Take for instance DMP -- most SysAdmins are lazy enough to read through documentation of the HBA they're using, configuration of the array and the required tunables. Most often, this is compounded by the fact that individual fiefdoms control the SAN, the switches and the array components themselves and that the poor SysAdmin had to assume all is set everywhere. There was once a very large Fortune 50 firm That's been having problems with a popular enterprise backup system (vendor/product witheld). The VP/CIO was almost involved in escalating the problem to that vendor's management because 18 months had passed, backups had not stabilized and their SAN almost always goes belly up. It turned out that it was a management and control problem -- individual teams were not cooperating and the poor consultants were ofetn times given the wrong settings and configuration of the infrastructure components. The problem was fixed when the CIO appointed a "Czar" of sorts that was given blanket authority over all these fiefdoms and who was knowledgeable enough. Case closed. Customer and vendor are happy.

LVM is admittedely easier and simpler to manage (fewer commands). VxVM has about 5x more commands and takes some time to get used to but my experience had shown that if one had an experience with any LVM (be it HPUX LVM, Solaris Diskuite, or VxVM) -- it is quite easy to adjust to other VM environments sans training. It is just that VxVM has emerged as more of a standard these days having no hardware agenda whatsoever and is markedly scalable and "safer" in all respects.

Online JFS is the Full Veritas Filesystem (VxFS) unless someone can dispute this. It is still by far the fastest filesystem and even has a "raw device emulation" mode by way of its QuickIO product. What I am wondering though is if OJFS can be swapped with VxFS or have credits for it if one were to purchase a Veritas Foundation Suite License (VxVM+VxFS).

I am aware of Tru64's best features' being integrated with future releases of HPUX. And I think that is the way to go for HPUX. I just find it a more compelling proposition to adopt standards specially if you're a multi-platform shop.

[Duncan Edmonstone]

Nelson,

Interesting discussion... I have a couple more points to add:


1) Yes you can get a Veritas Foundation Suite license for less on HP-UX if your already own OnLine JFS - talk to your Veritas account manager about this...

2) I agree that standards are a good idea, but REAL standards (IEEE,POSIX,RFCs etc.) not just de facto standards that certain companies (M$ being the main culprit) try and foist on us.

3) The only people you can buy VxVM off are Veritas, so just cos its available on multiple platforms doesn't mean your not 'locked in'. I'm not trying to argue that this isn't equally true of LVM (although almost identical versions based on different code bases exist for AIX and Linux), just making the point that 'standard' products that can only be purchased from one company are dangerous. In my opinion Veritas products are already overpriced for what they deliver, and Veritas seem to insist on a seperate license for nearly every piece of functionality. If VxVM were to become '*the* standard volume manager', I can only see this getting worse.

4) As the hardware we use becomes increasingly commoditised (sic?), being hardware independent is going to become less important - what will be more important are true industry standards which promote hardware *and* software independence, such as those being developed by SNIAs Storage Management Initiative (read about it here: http://www.snia.org/smi/home/ ) With software and hardware developed using emerging standards from SMI we can imagine a future where we can use any volume manager to manage any disk, and any volume managers UI to manage another volume managers volumes!

OK, OK, I've gone way off-topic, and got carried away, but still... its an interesting discussion...

Cheers

Duncan