Fibre Channel (SAN)

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Contributor
Posts: 31
Registered: ‎10-23-2011

SAN Storage replication

Hi Guys,

* For the network diagram, please refer to the attached *

The main purpose of this setup is to replicate storage between Site A and Site B. The SAN router used is a Brocade 7800 Series and the SAN switch used is Brocade 320 series. Replication is via a lease line link connection between both sites (6Mbps). Few questions regarding this setup:

1) The SAN router needs to be connected to the SAN switch or the Storage array? If the SAN router is connected to the SAN switch, do I need to configure anything on the SAN router port connected to the SAN switch, or I just connect the ports and fabric will merge automatically?

2) Besides transferring replicated data between both sites, the lease line will also be used for other applications. How do I ensure that there's enough bandwidth reserved for the replication data and at the same time, doesn't affect other critical applications that uses the link? Should I configure ARL (Adaptive Rate Limiting), QoS, etc?

3) The ensure that there's eavesdropping on the replication data, should I configure IPsec tunnel on top of the FCIP tunnel?

4) Any other configurations that I miss out?

Any useful advice and feedback is very much appreciated.

Rgds,

Dan

Valued Contributor
Posts: 931
Registered: ‎12-30-2009

Re: SAN Storage replication

1)

Both is possible for replication only.But you want application traffic aswell, connect the router to the switches.

Whether or not you have to configere the router or ports depends on how your going to use it.

Usually you create a Backbone fabric between the to routers and have seperate (edge) fabrics at sites A and B.

This is done to reduce fabric segmentation en mergin in event off intersite link failure.

To me it looks like your going to use the router to utilize FCIP for your intersite links.

Beware that in your current drawing, it looks like your also merging the fabrics on that site (and siteB)

Another reason to create an Backbone fabric or you have to implement something like virtual fabrics which could keep merging from happening.

2)

Your leased line is just 7Mbit (or 14 if you use compression). How much replication traffic are you going to generate and how much application traffic anyway?

3)

Some form of encryption would be nice, but make sure you compress the data before you encrypt.

Perhaps you have an VPN running on the leased line which you can use?

4)

My advice >

Create an backbone fabric between the routers, use LSAN zoning to export the needed devices to the other edge fabric.

Encrypt is possible and disered.

If your new to this config, read some manuals/best practices or better yet have someone do it for you or assist you with this job

Contributor
Posts: 31
Registered: ‎10-23-2011

Re: SAN Storage replication

Hi Dion,

Thanks for the valuable feedback. Yes, I'll be setting up FCIP between both sites (A & B). The main function of the 7800 router is only to transport replicated traffic across the lease line. I want to setup this connection as simple as possible. You did mentioned that I need to create a backbone fabric between both routers and to use LSAN zoning. Question is :

1) Why can't we allow both sites to merge the fabric? What complications will it cause?

2) From the previous message, you mentioned that ''But you want application traffic aswell, connect the router to the switches.'' Which application traffic are you referring to? Actually, the main purpose of this setup is, whatever new data that is written to the SAN storage at Site A needs to be sent over and written to Site B storage. Site B is a disaster recovery area.

3) We need to reserve approximately 2 Mbps for replicated data to move across the link.

4) Below are the steps that am planning to do for this setup :

i) Create domain ID, ip address on VE port

ii) configure the FCIP tunnel with compression and IPsec (if needed) on both ends and test connectivity via ping

iii) Create the backbone fabric and LSAN zoning on both routers

iv) Did I miss out anything?

Appreciate your advice and feedback as this is my first installation for FCIP, thanks.. 

Rgds,

Dan

Super Contributor
Posts: 635
Registered: ‎04-12-2010

Re: SAN Storage replication

Hi Dan,

Did you plan to use storage to storage replication only?

Did you have dedicated storage ports for this usage?

If so you can connect the storage replication ports to the 7800 and create via FCIP a 5th fabric without any routing stuff. So you do not connect the 7800 to your SAN switches!

This keeps everything simple. Disadvantage is that no server can use storage from the remote side or exchange any data.

If this function is needed later you can implement Ex ports and introduce FC routing later.

Andreas

Super Contributor
Posts: 635
Registered: ‎04-12-2010

Re: SAN Storage replication

Hi Dion,

your recommendation is OK and a valid solution with pros and cons as every other solution. Keep in mind that connecting a single backbone to a dual fabric design will degrade the HA solution non HA solution.

Yes, sometimes there is no other way.

Regards,

Andreas

Valued Contributor
Posts: 931
Registered: ‎12-30-2009

Re: SAN Storage replication

1) Well actually you can.

But depending on the stability off the leased line you end up with fabric which split and merge frequently.

This could impact both sites and surely impacts management as changes are halted or have to be done twice when the fabric is split

2) I figured

2) From the previous message, you mentioned that ''But you want  application traffic aswell, connect the router to the switches.'' Which  application traffic are you referring to? Actually, the main purpose of  this setup is, whatever new data that is written to the SAN storage at  Site A needs to be sent over and written to Site B storage. Site B is a  disaster recovery area.

as other FC traffic but now understand this is IP traffic, the usual IP traffic flow mehcanisms apply.

3) as mentioned in 2 use the usual IP traffic flow mehcanisms

4) unless you have targets or initiators in the backbone fabric you don't need LSAN zoning on the routers but in the edge fabrics.

Valued Contributor
Posts: 931
Registered: ‎12-30-2009

Re: SAN Storage replication

Hi andreas,

you're right, the router part with the leased line is a SPOF, but that's by choice as i've come to understand.

Super Contributor
Posts: 635
Registered: ‎04-12-2010

Re: SAN Storage replication

Yes the lease line is finally the SPOF by choise. But if you not connect the switches from site A & B to the 7800 means youstill  have two HA solutions and one fabric non HA including the lease line.

All options are open to introduce FCR later.

At the end it depends on the preferences of the thread owner.

Regards,

Andreas

Valued Contributor
Posts: 931
Registered: ‎12-30-2009

Re: SAN Storage replication

I agree that If only replication is wanted, deditaced replication storage ports on the 7800 directly ans in their own (5th) fabric is a neater solution.

But I disagree with you one the part that a single backbone fabric to a dual fabric design will degrade the HA solution non HA solution.

Sites A & B still have their independent dual fabrics, thus still HA and we didn't merge but used FCR. Yes the backbone is not redundant so that part isn't HA neither is the traffic that crosses the backbone fabric.

Super Contributor
Posts: 635
Registered: ‎04-12-2010

Re: SAN Storage replication

Hi,

for my understanding a high availability solution is a solution which is redundant and better it is resillient by design. A HA solution has no SPOF.

The backbone isn't redundant. This means it is the SPOF. A failure or problem of a single 7800 router will have an impact of both fabrics at the same site at the same time because a single router is providing FDs and XDs in both fabrics.

This looks not like a HA solution.

Both solutions are OK and will work.

Regards,

Andreas

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