Have you tried rebooting?

Brocade Principal Switch

// March 16th, 2010 // No Comments » // Technical Know-It-All

There has been quite a few confusion as to what Brocade Principal Switches do. So here it is, the principal switches have only 2 functions in the Brocade SAN Switches.

1. Provide time sync for all other switches in the fabric
2. Ensure that all Domain ID’s in the fabric are unique

Does it matter that the principal switch is a director class switch? Yes and no. It is obviously best that it is, but if it isn’t, no harm will be done to the environment. If the principal switch is down, re-election happens and a new principal is selected. Principals are selected based on

1. Lowest WWN
2. First switch on the fabric

To find out which switch is the principal, run the “fabricshow” command and look for the “>”. That will be your principal while the rest are “subordinates”.

Brocade CLI Zoning Tutorial

// March 11th, 2010 // No Comments » // Technical Know-It-All

Given that more and more features within Brocade SAN switches are configured using zones, thought I would share this quick CLI guide for those looking to script this.

Zoning is organised as such

- Every SAN device has a unique WWN (much like how IP devices have MAC addresses)
- WWN’s are then mapped to aliases
- Multiple aliases then form a zone
- Multiple zones then form a config
- Nutshell, WWN->Aliases->Zones->Config

So here are the steps to create a zones quickly using CLI.

1. Ensure you have noted down the device WWN and assign it a usable name for alias. WWN’s for devices can be found using “switchshow“. In this example, I will be mapping the following devices to the appropriate names

10:00:00:00:00:00:00:01 -> Server_HBA01
50:00:00:00:00:00:00:01 -> Storage_P01
50:00:00:00:00:00:00:02 -> Storage_P02

alicreate “Server_HBA01″, “10:00:00:00:00:00:00:01″

alicreate “Storage_P01″, “50:00:00:00:00:00:00:01″

alicreate “Storage_P02″, “50:00:00:00:00:00:00:02″

2. Next, we want to group these 3 members into a single zone so they can have access to each other. Let’s create a zone called “Zone_svr2_hba01_str_p01_str_po2″. Remember that zone members are case sensitive.

zonecreate “Zone_svr2_hba01_str_p01_str_p02″, “Server_HBA01; Storage_P01; Storage_P02″

3. After completing step 2, put the newly created zone into a config. For simplicity, I shall call this “Config_Test”. Again this is case sensitive.

cfgcreate “Config_Test”, “Zone_svr2_hba01_str_p01_str_p02″

4. Verify the zones using “cfgshow“. The zones should only show up under “Defined Configuration”. To make this zones active, you will need to enable it.

cfgenable “Config_Test”

5. Now if you run “cfgshow” again, you will realise that the “Defined Configuration” and “Effective Configuration” is the same. This is when you know the zones are activated.

6. To script this, you can simply prepare all commands in Notepad and open up a putty session then cut and paste it. You can also use SSH scripts if required.

The Buzz About FCoE and CEE

// February 26th, 2010 // No Comments » // Technical Know-It-All

The new buzzword these days in the Storage / Networking space is FCoE (fiber channel over ethernet) and CEE (converged enhanced ethernet). For those who are unfamiliar with the whole concept, in layman terms, it is a convergence of the traditional TCP/IP networks and traditional SAN networks into a single giant network.

While it is ideal from a C-Level perspective to streamline processes, reduce costs, go green and try doing more with less, at the technical level, it is never as easy as the vendors make it seem. Many industry experts have claimed that this new protocol will eventually replace the ever resilient FC Protocol and Ethernet. The jist of it is that, everything that has to do with “networking” will run on this newly improved protocol.

While this “could” be true, here are some points to ponder upon before taking the leap of faith to run your entire production systems on CEE and FCoE.

1. TCP/IP has never been known to be the most secure protocol (before I get flamed by the networking experts, it can potentially be secured with the right amount of tweaking). Compared to FC, while some may disagree, it is more secure in some ways (for starters, given that not every laptop will have an FC port to begin with, but having said that, more often than not SAN administrators take this for granted). By merging the 2 protocols together, suddenly we have a scenario where security might now be a concern to the traditional SAN guys.

2. Usually in large environments there is usually a Storage Team and Network Team. With the convergence, a discussion of job roles would probably emerge, and potentially job cuts (fingers crossed).

3. Standards. Currently, many of the protocols/standard are still very much in the review stage with IETF, T11 and the lot. Ethernet is stable today after many years of revision while CEE will take some time before reaching that level of maturity.

4. Physical infrastructures such as cabling are probably not ready today for a complete deployment. Many are still running cabling works that are barely rated for 1Gbit, let alone the 10-40Gbit as promised by CEE/FCoE. Also, existing Ethernet switches and FC switches are not meant to run this new protocol. Slowly and surely, vendors are releasing firmware updates to enable them to support the protocol in the legacy units, but having said that, the additional overheads of the protocol was never meant to run on existing hardware, so we might never know if it will be able to handle it. Newly released FCoE/CEE ready devices are slowly coming to market and today cost quite a fair bit.

Obviously, my little list above is not all conclusive, but my 2 cents of what I would probably be concerned about when thinking of rolling it out.

So in summary, I am not saying that CEE/FCoE is doomed for failure but maybe, just maybe, it is still too early for it to be totally viable in a full fledge production environment. I do believe that CEE/FCoE will take off and be a prominent protocol some day. Having said that I don’t think it will oust or replace traditional FC and Ethernet anytime soon as some major vendors are suggesting. It takes more than lowering cost and bandwidth to achieve total protocol dominance.

Just ask iSCSI and Infiniband.