EVA 4400 Availability Product??

[UselessUser]

Hi,

Quick question, we have a single EVA 4400 in our main datacentre. This will soon have VMware machines on it.

To create site resilience we are looking at buying another and putting it in another datacentre etc.

HP seem to like confusing people so I am not exactly sure what I need...

Can someone explain what these are/do?

Business Copy
Continous Access

Cluster Extension (Odd one this as it seems to imply Continous Access features and requires Continous Access to have been bought - but what does it actually add?)
Metro Cluster
Continental Cluster

Also what is required to use the Continous Availability? (i.e. is something plugged into the EVA and it replicates itself, or is there a host involved that does something? - bandwidth taken (I know this must depend on data being added to system - how would you calculate what is needed?)

As you can see... confused!

[Patrick Terlisten · Accepted solution]

Hello,

Continous Access = Synchronous and/ or asynchronous remote mirroring

Business Copy = Snapshots/ Clones

Cluster Extension = Automate failover with Continous Access

If you want to mirror the vdisks from one EVA to another EVA you need to purchase Continous Access. CA is licensed by capacity. The Cluster Extension EVA is only needed if you have Microsoft oder Linux clusters and you want to automate the failover.

Hope this helps.

Best regards,
Patrick

[Steven Clementi]

Lawrence:

Aside from having the additional EVA in a remote site, you would also need the same or similar SAN Infrastructure there as well as a way to connect the 2 sites.

Depending on how far apart the sites are... you will have different options to connect the sites. The bandwidth needed varies from customer to customer. You need to know a few values before anyone can even guess at the minimum necessary bandwidth.

How much Data is to be replicated?
What is the rate of change of the data?
Will you want to use VMware SRM in the environment?
The list goes on.

Continuous Access is not something you can plug in or touch. CA is functionality built into the EVA firmware and is enabled via licensing. It is EVA to EVA replication... no host required.

Same for Business Copy. You just apply a license to enable the functionality. BC is local disk replication (meaning you replicate your data on the same EVA).


Steven

[CLEB]

Lawrence, to manage Continuous Access you require a server that has Command View installed. If you only use Array Based Management you won't have the option of creating/managing DR groups.

[UselessUser]

Hi,

Thanks for the replies.. I am getting there...

With Continous Access (In regards to VMware etc)...

If I had a setup with a physical host with 2 HBA's each going into 2 switches, and each switch has a link to a single EVA with 2 controllers, I would have 4 paths.

If I then added another EVA with 2 controllers using Continous Access, would I end up with more paths to the same storage? (If so how many?)

Also how is the data replicated, I take it data is sent to one controller and then that controller asks another controller (On the other EVA to replicate that write request?)

Delays etc are dealt with how?!

[Uwe Zessin]

There are 4 _other_ paths, but a CA-EVA configuration does not use impersonation (e.g. WWPN spoofing). One server MUST NOT see the source virtual disk and a read-only replica.

The process to 'switch over' is called a failover and a disruptive operation, because the data comes alive on different SCSI paths.