LVM v/s VxVM

[Bharat Katkar]

Hi Collegues,
I need to understand all possible difference between this two Subsystems and their relative advantages and disadvantages.
Also when one should really go for VxVM rather than LVM. I have pointed out some but want to explorer them more and more.

Thanks in advance for your valuable suggestions.
Regards,
Bharat

[Michael Tully]

Have you read this discussion?

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=211299

[Peter Leddy_1]

Hi Bharat,

Fon't know if you have seen this or not but try the following doc, it has a section on some of the differences between the 2(called Command Differences), also try searching docs.hp.com(If you haven't already) you may find some other docs that could be usefull.

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/5971-4768/5971-4768_top.html&con=/hpux/onlinedocs/5971-4768/00/00/10-con.html&toc=/hpux/onlinedocs/5971-4768/00/00/10-toc.html&searchterms=lvm&queryid=20040812-021440

HTH,

Peter

[Sanjay Kumar Suri · Accepted solution]

Some of the difference are:

1. VxVM is supported only on HP-UX 11i.
2. Boot disk is not supported in VxVM.
3. VxVM has its own GUI tool unlike SAM which can be configured through SAM.
4. LVM supports 3 way mirroring (RAID 1) whereas VxVM supports up to 32-way mirrors for each partition.
5. RAID5 is supported in VxVM.
6. VxVM supports dynamic conversion of partition from one format (say RAID 5) to another (mirror).
7. VxVM supports (as is LVM) dynamic multipathing + capability to utilize both paths simultaneously.


sks

[Pete Randall]

It should be mentioned that all those nice things that Sanjay pointed out that VxVM can do for you, only come in the purchased product. The free base product offers no mirroring, etc.


Pete

[Rita C Workman]

Options--the others have mentioned.

The thread Mr. Tully points to was from a year ago...

...back then I said I would probably eventually go VxVM. It's a year later - I am still at LVM - and I am not moving any time soon.
Fact is, I believe I will hold on good old faithful LVM until the time comes when I am 'forced' to change. Heck...I'm still using the old Jetadmin character mode.

Just sign me,
Still Luv LVM,
Rita

[Alzhy]

For starters, I would say both are Excellent volume managers. However, it "depends" on the environment and the folks supporting it. Most HP-UX shops that use Veritas VxVM based products are shops that also heavily use Sun Solaris.

For an in depth comparison, one must take into account Veritas Foundation Suite (which is the Full VxVM + Veritas Filesystem a.k.a. Online JFS) and on the LVM Side -- MirrorDisk/UX and Online JFS (which is Veritas Filesystem OEM'd).

Closely comparing, VxVM will have significant advantages over LVM:

1. Closer affinity with Online JFS (aka VxFS) since both are Veritas Products
2. Works seamlessly with Oracle Disk Manager (ODM).. so DBA's can manage and optimize storage use and layout
3. Dynamic MultiPathing (DMP) -- for path protection and load balancing accross FCs
4. Mirroring is a whole lot faster (multi-threaded). With LVM one can only have a single mirroring process going on... A very good alternative to in-array solutions like Business Copy or SRDF/Timefinder... Even faster with the FlashSnap product.
5. With the BASE (free) version you can already mirror your VxVM managed boot disk (Yes Sanjay rootability is already supported as well as Ignite/UX)
6. Online relayout of volumes that is not possible with LVM.
7. Easier to administer IMHO (via the VEA)
8. Many more layouts to allow for building of VOLUMES out of LUNS that are higher performing .. ie. layered volumes.


Even with the base version, a whole lot can already be done with VxVM not to mention mirroring (aka protection) of the OS disks come free. The following is a link to what features are avaiable for the BASE as well as the other licensed products:

http://docs.hp.com/hpux/pdf/5187-1373.pdf

[Sundar_7]

I am not going to add anything new.

But yes you can have VG00 under VXVM (i.e rootablity) is supported).

With LVM and MirroDX/UX, you can only do RAID level 0 and 1. There is no true mirrored stripes (only extend based). But with VxVM you can do even RAID level 5.

But for someone who has been working in LVM for years, I find it relatively cumbersome to execute some of the tasks, since you have to have daemons running.

Also the commands are not as administrator friendly as LVM :-).

I am sure people who have used VxVM extensively can tell you a different story. just my 2 cents.

[Alzhy]

Well I have been using VxVM for years and I see no difference at all in complexity using CLI on both VxVM and LVM.

My advice always on HP-UX 11i environments is if the site does not have any need of the features that VxVM offer AND they feel more comfortable with LVM -- then LVM is it.

The compelling advantage though for 11i systems is with the base VxVM (which comes bundled free) -- you can use it to protect your OS disk -- since you alredy have the ability to mirror at least your boot/root disks -- with LVM , you need to purchase MirrorDisk/UX.


And did you know that VxVM/LVM can co-exist? You could have LVM manage your bootdisk and your SAN disks managed by VxVM. And if you're already running a multipathing software like SecurePath/AutoPath AND using a SAN Array (i.e. EVA, XP).. then who needs the full version of VxVM?

[Sundar_7]

Nelson, You see no difference in the complexity between LVM and Vxvm ? wow - is it just me? - I hope not - I am sure many will agree LVM CLI is much easier to remember than VxVM CLI.