Oracle RAC and EVA

[Hasan_9]

Hello,

How can I use 8 Host port in EVA8000 simultaneously? For example, if we have 10 servers and want to install Oracle RAC on all of them, we will definitely need, more than 2 Gb/s I/O connection to shared storage! If we have an enormous disk array like EVA 8000, how can we use all of its capacity? Is there any software that balances the traffic between 8 host ports or we have to divide Oracle table spaces through different host ports?

[Steven E. Protter]

Shalom Hasan,

Add a fiber switch to this setup and that will increase the number of ports you can connect to this device with.

Brocade makes good ones. McData does as well.

SEP

[Hasan_9]

Thank you Steven,

However, My question is not about SAN connectivity or number of ports. I want to know how can we use all the Host ports of EVA for setting up an Oracle RAC? If we connect all the servers to a SAN switch and also connect EVA to it, we will have 4 connection to disk array. Now, in a big RAC environment, We must balance the load between these 4 ways to disk array. How should we do for this issue?

[Chan 007]

Hi,

Switches does this activity.

Try having a logical name for all these instances and use load balancing switches.

Also can you pls let me know..

YOu have One RAC instance with Applications servers or you have all RAC servers?

Cheers..007

[Steven E. Protter]

I see Hasan, sorry for the misunderstanding.

Load balancing on your array:
http://h18006.www1.hp.com/products/quickspecs/11402_na/11402_na.html

http://h18006.www1.hp.com/storage/evasoftware.html

http://nwc.compliancepipeline.com/news/163105342

As I thought, its a function of he disk array. If load balancing on the array is not possible, you can try and do it yourself by projecting the amont of database transactions done by earch server and laying out your SAN in a logical way.

SEP

[Hasan_9]

Thank you All,

I did not get the point, how a switch can balance a load between host ports on a disk array.
Let me explain my plan some more. This is an Oracle RAC system with 10 servers. All of the servers handle a same database ( 10 instances for one database). So they have to access the same datafiles on shared storage.All the servers and disk array connect to a same SAN switch. If for example we have one LUN on disk array, I will see it on OS as 4 different disks (like c6t0d0, c7t0d0, c8t0d0, c9t0d0), because we have 4 host ports on disk array and each of them determine a different path to LUN. Now, I have to select one of them on all of the servers (like c6t0d0) for the purpose of making datafiles.Choosing one of these disks (like c6t0d0) means we will use just one of the host ports on disk array, because we access the disk through just one path. One host port can handle maximum 2 Gb/s,but enormous disk arrays like EVA 8000 can handle 800 MB/s I/O bandwidth.
In a huge RAC (with 10 servers) using just one 200 MB/s will cause bottleneck on I/O.
So we have to find a solution for using all of host ports on disk array simultaneously for the purpose of accessing to same datafiles. Securepath is not useful. It is for high availability. I think we can create more than one LUN and distribute datafiles on these LUNs and access them through different host ports. What is your idea? Is there any better solution for this issue?

[Sanjay_6]

Hi,

Have you looked into EMC Powerpath,

http://www.source.be/partners/DataSheets/EMC/PowerPath_DS.pdf

Hope this helps.

Regds

[Uwe Zessin]

Correct, a simple Fibre Channel switch does not do load balancing between host ports of a disk array.

Secure Path is useful, if you like to use its driver for load balancing between host ports. The other way is to create multiple virtual disks, divide them on both controllers, possibly choose manual paths with PVlinks, and combine them with LVM.

I doubt than EMC PowerPath works with a HP EVA.

[Bill Costigan · Accepted solution]

First I just installed powerpath 4.3 and it lists a setting for the eva, so it sound like it might support the eva.

Second, You didn't mention if you were using LVM or you were just accessing the LUNs as device files.

If you are using LVM you could add 8 PVs into the vg each pointing to a different host port. Then you could create your lvols using extent based striping across all 8 PVs. Assuming the LVM extent size is 8MB then ever 1/8th 8MB chunk will be accessed through a differnet host port.

If you are not using LVM, but have 10 systems accessing the same LUN, you could divide your systems across the host ports.
e.g. the six busiest hosts each use a dedicated host port and the other 4 share the remaining 2 host ports.

[Hasan_9]

Thank you Bill,

This will be a real application cluster, so I have to use one of RAW or SLVM as shared storage.

Hasan