Have you tried rebooting?

SAS vs FC Disks

// November 8th, 2010 // No Comments » // Technical Know-It-All

In recent times, there has been much said about the future of SAS (serial attached scsi) vs FC (fiber channel). Don’t get me, I’m not saying that FC is dropping dead tomorrow. It is probably still relevant for another 3-5 years, but I for see the future in SAS disks.

Here’s my quick lowdown on it. In no way conclusive, but its something to ponder about.

1. Why SAS?

Why the crap not? SAS is a fraction of the price cheaper, has a strong roadmap moving forward with 6Gbps today, and moving ahead in the future to faster backends. FC has been at 4Gbps for the longest time and have not moved an inch since. It also doesn’t have a roadmap to go any further beyond 4Gbps.

SAS also comes in 2.5″ variants. Have a real estate or green issue? Here’s to a smaller, lighter and greener media.

2. But SAS is Tier 2 disks

How do we define Tier 1 from Tier 2 disks today? Reliability and performance.

In terms of reliability, SAS disks are manufactured and developed to the same specifications of a FC Disk. The only difference is the connector / interfaces at the backend. The likelyhood of a SAS drive failing is the same as a FC drive failing.

Performance, used to be a big discussion point because SAS ran at 3Gbps, but now with 6Gbps and a non-arbitrated loop architecture, it is blowing FC off it’s socks. No discussion there.

3. SAS is SATA’s expensive cousin

Very good observations there. True! The commonality here is “Serial”, and because of that, you can now intermix SAS and SATA disks in the same enclosures. No need for different enclosures for different disk types and no more for funky FATA disks. Go forth and intermix. Beyond that there is nothing similar with regards to the built of the drives.

4. Not convinced still?

Surely vendors like Hitachi Data System’s (HDS) or even IBM can’t be so far off their socks. Hitachi for example have a Hard Disk’s Division that only builds drives. Their business is far far larger than their HDS counterparts. So do you think they will just drop their FC product roadmap just to help out a smaller subsidiary of theirs? Or do you think they are considering the shifting market trend?

Ultimately, there is always the opinionated Google that speaks for itself.

Free SAN Technical EBooks

// March 23rd, 2010 // No Comments » // Technical Know-It-All

I came across 2 ebooks that were free recently. Not too many things are free these days but I must say these 2 books are pretty good entry level books. Enjoy!

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.

Brocade SAN Health Tutorial

// December 10th, 2009 // 2 Comments » // Technical Know-It-All

As promised before, I will try to explain in detail how to work Brocade SAN Health. Just a recap, Brocade SH is an exceptionally informative tool that allows you to capture performance, and configuration data from Brocade and McData SAN fabrics. It will then take this data and churn out a very useful Visio diagram and an Excel file.

Alright, let’s start!

1. Firstly, you would need to download the tool from the Brocade website. Once downloaded, the install takes like 3 secs. Fire up the tool and you will see a screen like above.

2. Click on “New”, and it will prompt you to fill up all your contact details. Fill it in accordingly.

3. Click on the “Report Return” tab, and fill in the your email address. It is “IMPORTANT” to get your email address right here because ultimately, this is where your report is going to be sent to.

4. Click on the “SAN Details” tab next, and give your audited SAN a name.

5. Next click on “Add Switches”. Input the IP addresses and login details of the switches. Usually, you would only require 1 switch from each fabric. Once it successfully logs in to the first switch, the rest is discovered in-band.

6. Click on “Fabric Details”. Here fill up fabric name, vendor details, and the duration of this audit.

7. Verify that all the “Green Smiley” faces are there. If not click on each of those and make sure they are green. When that’s done, you are ready to do a preflight check! Go to the “Start Audit” tab and run “Pre-Flight Check”. If pre-flight is good, the “Start Audit” button will be available.

8. It will then start running. Depending on how long you want it to capture, you can probably minimise the window and let it run in the background. I usually recommend 24 hours just so you get a complete trending of the peaks and lows.

9. Once complete, it will encrypt the file (so it is safe to be sent across the Internet). Keep clicking “Next” and read the on-screen instructions.

10. The last screen will tell you where the <filename>.BSH ( Brocade San Health) file is saved. You will then need to forward the *.BSH file to SHUpload@brocade.com. This file will then get processed in the backend by Brocade server’s and then you should receive a reply in 24 hours (more often than not, you will get it in 4-5 hrs). In the event that you don’t hear from them in that time frame, email SHAdmin@brocade.com and let them know the filename of the *.BSH file, they will let you know if it’s in the queue.

That is it! Simple!

Many of my customers swear on this, and they do it on a weekly basis just to keep their SAN environments in check. So give it a go. Things that are FREE are rarely this good & usefull….

P/S : You cannot capture performance data from McData fabrics and there are no roadmaps for this.

SAN Assessments

// November 20th, 2009 // No Comments » // Technical Know-It-All

Just conducted another SAN Assessment this afternoon. While SAN Assessments are generally tedius and boring projects, I do get a sense of achievement and pride when I help another customer spot out an issue that nobody has managed to.

So I thought I would share a couple of goodies for SAN Administrators out there who wants to give their SAN a quick assessment and see how they are doing.

First get to the Brocade website and download this tool “SAN Health”. Just a side note, this tool only collects info from Brocade, and McData fabrics. Performance captures are only enabled on Brocade fabrics, not McData. If you are running Cisco, you are somewhat out of luck. You could still use SAN Health to capture Cisco fabrics but don’t expect it to return much. The capture utilizes SSH/Telnet to access the switches/directors and dump data off them. Once thats complete, you will need to upload it to Brocade and you should receive an email in 2-3 hours time from Brocade. The email will contain a zip file with and Excel spreadsheet and a Visio diagram.

I will try to post some screenshots when i get the chance.

Any how, there are many things to look out for in the excel spreadsheets from firmwares revisions to errors. For firmware revisions, check with your OEM vendors to see what is the latest supported versions and compare it against yours. For errors, pay additional attention to CRC errors, and Encoding Out errors. If you have high encoding out errors, chances are you have a faulty cable. If you get a combination of both, good chance you might have a SFP issue.

Feel free to post comments if you need more help. Meanwhile, if you need help with any SAN issues, you can search for Brocade Services APJ on Facebook. A few Brocade Consultants monitor that for questions.

UPDATED : Brocade SAN Health Step-by-Step