EMC disk and LVM

[Tanmay_1]

Hi,

Is there any option in LVM to use an EMC disk? My idea was I can use it normally as I use any HP disk. Please help.

While creating 3 partitions to be used by Oracle database, redo log, and log what is the best way to create file systems? Any prefered blocak size or some thing?

What are the kernel parameters to be modified while handling a large Oracle DB? Say I have 2 GB RAM, any thumb rull for these parameters?

Tanmay

[Sundar_7 · Accepted solution]

Hi Tanmay,

Yes you can use EMC disks just like any other disk. If the storage is connected via SAN, you might have to do some kind of Zoning/Lun-masking to make the EMC volumes visible to the host.

Once the EMC volumes are visible to the host,LVM can deal with them just like any other disk.

Couple of things

1) Set the bad block relocation to NONE. By default it is set to YES. Use the -r N option with lvcreate. This is needed since typical EMC arrays have inbuilt mechanisms to handle bad blocks and you dont want two different sources (LVM and EMC) handling the bad block relocation at the same time !

2) Default PV timeout values for the PV is 30 secs. This may not be ideal in some SAN environments. If you get frequent SCSI Read/Write timeout errors from the LVM/Kernel, increase the PV timeout to a higher value

On creating filesystems

1) Consider seperate volume groups for Database, REDO log and log.
2) Decide if you want to use the RAW LVs or filesystem
3) If filesystem, consider creating distributed volumes (Extend based stripes).
4) You can leave the default block size for the filesystem. You will have to enable largefiles option for the filesystem
5) Read the man page of mount_vxfs and understand the various VXFS mount options and choose which one is best for you.

On the Kernel Parameters

1) Typically you would want to keep the process,inode and file system tables to a reasonable value.
2) Ensure you have enough virtual memory and set the SGA to an approriate value.
3) IPC parameters (Message Queue, Semaphore and Shared memory) parameters need to be tuned
4) Set the buffer cache sizes to an optimal value.

This is all I can think of as of now :-). good luck !

- Sundar

[Tanmay_1]

Owa!!!! Some times I think I will speak with you. Is it possible? My email is tanmaybanerjee@yahoo.com

Tanmay

[Pratyush Paul_1]

TB - (tan)

EMC disks are just simple disks. They are just not local to your system, they are either connected to your system thru fiber channel or thru a fabric switch. The task you are trying to implement should be on raw LVMs not on file systems as it is going to take a huge performance hit. Again you have to make a choice. There are some patches for HP-UX 11.0 or 11.i and it should be found in the link below

http://www.oracle.com/technology//index.html

You need to install these patches before you install oracle onto your system.

For Kernel parameters :-

a. buffer cache at an optimum
b. SGA at an optium value ( the above site will have examples for you)
c. Inodes, nfiles, nproc, shmem=mem_max etc (all generic stuff) should be reasonable.

please let me know how it works.

Cheers

Pratyush Paul