Monthly Archives: March 2013

SCSI, (P)ATA, SAS, NL-SAS and SATA, what’s the difference? (part 1)

Everybody needs storage space nowadays. Whether it is used for high performance computing or simply storing family snapshots, we all need room to store data which is important to us.

In the old days (the 1990s) things were fairly easy: you had either ATA or SCSI. The much older RLL and MFM are now called ancient and therefore not talked about in this article. ATA was mainstream for about 10 years and SCSI was expensive, but also very fast. Both standards used a flatcable and the data was sent to and from the drive in parallel. But when speeds increased the timing of each of the separate signals became difficult and just like cd players in the 1980s manufacturers started using serial lines. This meant that higher speeds could be accomplished and also that the huge flatcables were now traded in for much smaller cable, which improved the airflow as well.

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What is trending in Q1 and what can we expect in Q2 of this year?

What was trending in Q1 of 2013 and what can we expect in Q2?

I made a few observations over the past weeks and I’m seeing a few topics that got my attention:

  1. EMC now has a community appreciation program called EMC Elect and I’m one of the 10 original founders! I blogged about that here:
  2. EMC announced new SAS drives for the formerly FC-only based VMAX
  3. VCE announced new vBlock models. I wrote a little blog post here:
  4. a new Cloud Solution from EMC: VMAX CE. I wrote a blog about that too here:
  5. EMC VFCache is transformed into ExtremSF and faster and larger products will be made available. Also the XtremSW software suite is introduced that eventually is able to use third party flash card to be used as cache or DAS storage
  6. EMC introduces its XtremIO, all flash array with true inline deduplication

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The importance of keeping fibers clean

Fiber patch cables seem to be very forgiving, when light shines through everything is great and everybody’s happy, right? Wrong!!!
You shouldn’t underestimate the importance of keeping the ends of patch cables and the SFPs clean, since the actual diameter of a fiber is either 9 or 50 (or even 62.5) mu (micron).


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testing a delayed post with the auto tweet feature….

Wrote this post on Tuesday March 5 at 11:50AM CET, but delayed the post to go live at 12:00.

testing the auto tweet feature…..

my appologies for the inconveniece, but I need to test.



How to bring down an EMC VNXe (as if you ever want to do so)

If you somehow need to get some work don on your power feeds to your data center and the VNXe needs to be shut down, you need to manually shut down the machine before starting the work on the power lines. But knowing CX and VNX, this proved to be a challenge for me since the e model doesn’t have Standby Power Supplies. These SPSs used in CXs and VNXs do the work for you: when you turn the power switch on the SPSs or simply cut the power feed to these SPSs, the SPSs send out a signal to the Storage Processors, which will then flush the write cache to the vault after which the SPs will shut down nice and orderly.

But how do you do this on a VNXe model?

The best way is to do this from your desk! you don’t even have to get up and walk to the VNXe at all! There are two ways you can shutdown the VNXe.

  • Through the Unisphere GUI: Settings > Service System > Select Shutdown and click “Execute Service” action. This option was introducted in the operating system version 2.2.0. This will shut down the system completely and only the Power Supply’s ‘power LEDs’ will remain on.
  • Through Unisphere CLI using following command:

uemcli -d <IP_address> -u service -p <Service_password> /service/system shutdown

The Unisphere CLI (UEMCLI) should be downloaded from the EMC Support website and should be installed on your pc (Windows/Linux/Solaris/Unix). After installing this CLI you can execute the mentioned command to shutdown the VNXe. There is a Unisphere CLI user guide available on the EMC Support website.

In the older versions of the VNXe operating system there was no CLI option to shutdown the unit. The svc_shutdown command from the console (Putty) was the only way on those older machines. However this will not completely power down the system, it will unload all software from memory. After issueing this command a power loss won’t damage the data (like LUN corruption, OS image corruption, cache dirty etc.).