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LVM vx VXVM for Oracle datafiles

 
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Srikanth Arunachalam
Trusted Contributor

LVM vx VXVM for Oracle datafiles

Hi,

We are setting up Oracle 10g on HP-UX 11iv2.
We have purchased license for VxVM and DMP for VXVM and we are using EVA6k for our storage requirement. The size of database is 2tb which will reside in one large LUN of EVA6k.

Before creating mount points for oracle data files, would like to confirm, If there is any specific advantage of using VxVM over LVM. Are there any specific advantage in terms of performance, recovery of disk space etc.
11 REPLIES 11
inventsekar_1
Respected Contributor

Re: LVM vx VXVM for Oracle datafiles

hi srikanth,
refer this thread for VxVM or LVM comparison:

http://forums1.itrc.hp.com/service/forums/bizsupport/questionanswer.do?threadId=147857
Be Tomorrow, Today.
Steven E. Protter
Exalted Contributor

Re: LVM vx VXVM for Oracle datafiles

Shalom,

No advantage using VxVM except it may be supported longer. There are rumors about the death of LVM from time to time. They are always proven false.

It makes no difference to Oracle.

SEP
Steven E Protter
Owner of ISN Corporation
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Founder http://newdatacloud.com
inventsekar_1
Respected Contributor

Re: LVM vx VXVM for Oracle datafiles

for your question:
----------------
If there is any specific advantage of using VxVM over LVM
----------------
this can be answer. i copied this from that thread only.
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There are some features in VxVM that are not available from LVM that should be the points for consideration when you decide to move. This is from some text that I saved up early this year. I particularly liked the DMP feature in VxVM that allows you to do load balancing (this feature has to be purchased separately) that LVM does not provide.
- A JAVA-based administrative GUI. The Storage Administrator can run either as a system application or from a web browser.
- Provides simple, goal-based storage allocation.
- Tracks progress of system recovery operations by monitoring task creation, maintenance, and completion. The Task Monitor allows you to pause, resume, and stop as desired to adjust the impact on system performance.
- Dynamic Multipathing (DMP) for Active/Active Devices. Provides high availability to data on disks with multiple host-to-device pathways by providing a disk/device path failover mechanism and by providing load balancing. (LVM supports path failover but does not support I/O balancing.)
- Multiple mirroring allows up to 32 mirror copies of a volume.
- Mirrored stripes (RAID-1 + RAID-0) and striped mirrors (RAID-0 + RAID-1).VxVM both support the combination of mirroring and striping.
- The hot relocation process, vxrelocd(1M), automatically moves failed subdisks to available disk space within the same disk group. This allows a system to react automatically to I/O failures on redundant (mirrored or RAID-5) VxVM objects, restoring redundancy and access to those objects without administrative intervention.
- Online Data Migration allows storage regions on physical media to be dynamically moved to other physical devices.
- Online Relayout allows you to change logical data configuration while online; for example, you can change a RAID-5 layout to a mirrored layout if you have enough disk space. The volume data remains available during the relayout operation.
--------------------------------------------
Be Tomorrow, Today.
Srikanth Arunachalam
Trusted Contributor

Re: LVM vx VXVM for Oracle datafiles

Hi,

The EVA6k storage works takes care of load balancing and manages bundles of disk in the storage arrays.

The only advantage I see in VxVM is the sub-disk is of variable size when compared to the physical extends in LVM.

Is there anything that physical extends should be propotionate to that of size of volume in case of LVM. If the size of volume is 140GB, should that be 16m instead of 4m.
If I have largefile system, will there be larger physical extend.

Thanks,
Srikanth
User data is contained in physical extents in LVM and subdisks in VxVM.

The LVM physical extents are of a fixed length. LVM allocates space in terms of physical extents which is a set of physical disk blocks on a physical volume. The extent size for all physical volumes within a volume group must be the same, and is usually 4 MB.

VxVM allocates disk space in term of subdisks which is a set of physical disk blocks representing a specific portion of a VxVM disk and is of arbitrary size.
F Verschuren
Esteemed Contributor

Re: LVM vx VXVM for Oracle datafiles

2tb is the larged filesystem you can create on standart hpux lvm if you have plans to enlarge bigger than 2tb you must chose someting els...
F Verschuren
Esteemed Contributor

Re: LVM vx VXVM for Oracle datafiles


HP-UX Release Maximum Supported File Maximum Supported File System
Size Size
=====================================================================
10.01 2 GB 4 GB
10.10 2 GB 128 GB
10.20* 128 GB 128 GB
11.00* 128 GB 128 GB
11i* 128 GB 128 GB

For JFS or VxFS:
----------------

HP-UX JFS Disk Layout Maximum Maximum
Release Version Version Supported File Supported File System
Size Size
==================================================================
10.20 JFS 3.0 Version 2 2 GB 128 GB
10.20 JFS 3.0 Version 3** 128 GB 128 GB
11.00 JFS 3.1 Version 2 2 GB 128 GB
11.00* JFS 3.1 Version 3** 1 TB 1 TB
11.00 JFS 3.3 Version 2 2 GB 128 GB
11.00 JFS 3.3 Version 3** 1 TB 1 TB
11.00 JFS 3.3 Version 4 1 TB 1 TB
11i JFS 3.3 Version 2 2 GB 128 GB
11i JFS 3.3 Version 3 2 TB 2 TB
11i JFS 3.3 Version 4** 2 TB 2 TB
Srikanth Arunachalam
Trusted Contributor

Re: LVM vx VXVM for Oracle datafiles

Hi,

Agreed on file system size. What about the physical volume size limit. We have planned to use only one large physical volume and use multiple file system of maximum size not reaching 1.5gb.

Thanks,
Srikanth
Alzhy
Honored Contributor

Re: LVM vx VXVM for Oracle datafiles

Congratz on your decision on the EVA6K (now active-active and "industry standard multi-pathing friendly") and VxVM.

Since you mentioned HP-UX11i R2, you are most likely running VxVM 4.1 and VxFS 4.1 - if you are at 3.5 for both - I suggest you go for the 4.1 release. If you ignite/imgae your server from the latest 11iR2 release media - you should be at 4.1 for both VxVM and VxFS.

Before I give you the advantages and pluses of VxVM, let me say to you your plan of just having one LUN (2TB) to house your database is I think a bad idea. Many many reasons -- backups, snapshot technologies, performance and flexibility of your instance will be affected.

Now what are your advantages to using VxVM in concert with VxVM (and VxFS for that matter if you are using cooked storage?):

- You can have storage layouts (volumes) that can be far better performing than what LVM can offer (i.e. layered volumes, etc.)

- DMP (the path protecttion and load balancing feature of VxVM) is vastly superior than LVM. If you have several paths to your Storage LUN - DMP will distribute loading. Compare that with LVM's AP and PVLINKS...?

- Mirroring (and FlashSnap) facilities are vastly superior, scalabale and "safer" than LVM. You can use VxVM to mirror between different array vendors and opt for host based mirroring/snapshot or BCV solutions - avoinding Vendor Lockin to "in-array" solutions.

- Online and safer options to perform structural changes to your storage volumes - whether raw or cooked (VxFS).

- Data Migrations will be a whole lot easier.

- You no longer have to be concerned with changES TO disk paths or device cXtYdZ names. No more dealing with mapfiles and vgexport/vgimport.


Hakuna Matata.
Srikanth Arunachalam
Trusted Contributor

Re: LVM vx VXVM for Oracle datafiles

Hi Nelson,

2 clear informations I would like to have :-
(1) Advocating for more LUNs to house the database in EVA6k (considering the advantage of EVA6k).
(2) A more pricise point to prove that VXVM is much more preferred solutions.

Can you please throw more light on the following said points.
(1) How will the storage layout be far better performing than layered volume of LVM.

(2) Regarding mirroring, what is avoiding vendor locking to "in-array" meant by please.

(3) Please explain on this.
"You no longer have to be concerned with changES TO disk paths or device cXtYdZ names. No more dealing with mapfiles and vgexport/vgimport"...dont we still use vgdg import and export in vxvm.

Thanks in advance for your answers.