Archive for August, 2010

Figuring Out Your Replication Bandwidth

August 29, 2010

Replication in the IT space is pretty common place.  We replicate just about everything from SAN’s and NAS arrays to backup appliances.  Eventually during discussions around replication the “how big of a pipe do I need” question has to be addressed.  To figure this out is not complicated but it can be a pain to convert everything into the correct units.  In the case of replicating Avamar or DataDomain arrays we just need to find out what the daily change rate of the data is and how much time the client has available for replication.  Below are some approximate numbers that should help make the math quicker and easier.

Using a T1 as a baseline:

T1 = 1.544 Mb/sec = 10MB/min = 600MB/hr

In 1Mb/sec Increments:

1Mb/sec = 7MB/min = 420MB/hr

2Mb/sec = 14MB/min = 840MB/hr

3Mb/sec = 21MB/min = 1260MB/hr

4MB/sec = 28MB/min = 1680MB/hr

Keep in mind these are theoretical maximum numbers but from here you can roughly figure out either what size pipe is needed or how much time is needed to accomplish your replication goals.

Here are also a few usefull links:

Data Transfer Link Converter

T-Carrier Descriptions


Change, Change, Change – VMware per VM Software Licensing

August 13, 2010

If you haven’t heard yet, VMware will be changing its licensing model (yeah, again) for some of its vCenter based products like Site Recovery Manager.  At least the per processor licensing model for vSphere will stay the same.  When I first heard about this change my first thought was, WT* is VMware smokin’ over there!  Maybe they’ve been hanging out with the guys from Microsoft’s licensing geniuses too long because it certainly seems like they’re going down the “complicated and confusing is best (at least for VMware)” licensing path.  Of course they put a nice spin on the new licensing scheme when it was announced.  Something to the effect of, “to better align licensing with the way our customers do business” or “to provide a more cost effective model for our software”.  You know, the kind of stuff that generally pegs your BS meter right out of the gate.

Now all that being said, as I had a few converstations with various clients over the past few weeks I realized there are some benefits to this new licensing. Let’s look at a situation and how it would affect you financially.  I’ll be using LIST pricing for licensing and 25% of that cost as 1 Year Maintenance cost, so keep that in mind.

Client X:

  • 3 VMware Hosts (dual proc) at Site A
  • 30 VM’s
  • 3 VMware Hosts at Site B

If we look at traditional SRM pricing for this scenario it would look something like this:

  • 6 Licenses of SRM                            $1750 x 6                              $10,500
  • 6 Production Support                     $1750 x .25 x 6                  $2,625
  • Total                                                                                                         $13,125
  • Total VM’s protected = 30
  • Cost per protected VM = $437

If we run this same senario under the new licensing plan it looks like this: (pricing is not offical)

  • 30 Licenses of SRM (per vm)         $450 x 30                              $13,500
  • 30 Production Support                     $450 x .25 x 30                  $3,375
  • Total                                                                                                            $16,875
  • Total VM’s protected = 30
  • Cost per protected VM = $562

As you can see, the new licensing program really doesn’t benefit YOU, at least financially, in this case.

If we look at this from a standpoint of not needing to protect ALL vm’s then things look a little different.  Assume we need to only protect 10 vm’s instead of all 30.  The new licensing can help you in this case.  And, YES, I understand that you could restrict these 10 vm’s to one host and only license that host but in this case I’ll assume we’re utilizing DRS and need to license all hosts for SRM.

  • 10 Licenses of SRM (per vm)       $450 x 10                              $4,500
  • 10 Production Support                   $450 x .25 x 10                  $1,125
  • Total                                                                                                          $5,625
  • Total VM’s protected = 10
  • Cost per protected VM = $562

So if you were thinking about purchasing SRM for your environment now may be a good time to evaluate exactly what you need to protect and do some calculations around which licensing model best fits you.  As of September 1, all new purchases of SRM will be under the per VM model.  If you get grandfathered in prior to that you will be able to continue with the per processor model.

EMC FAST Suite Version 2 – Available Now

August 12, 2010

I blogged earlier about designing with storage pools vs traditional raid groups.  I’m sure you were all overly excited to read about that – both of you.  Well one of the biggest benefits of using storage pools is now finally available from EMC.  I’m talking about the latest release of the FAST from EMC.  This is really two products, FAST Sublun Tiering and FAST Cache.  With FAST Sublun Tiering you can now create storage pools with EFD, FC and SATA drives and let the array do all the work in regards to deciding which data needs to run on which tier of drives.  If you have part of a database that constantly blasts 2500 I/O all day long, no problem, it gets moved on to the EFD tier.  Got some freaky adult entertainment type files that the creepy guy two cubes down from keeps on his home drive for ole time sake – yep that will be hanging out on SATA (after several virus scans I hope).  For most environments this approach really makes sense and really makes life easier.  Let’s face it, you probably have no idea what the I/O graph on most of your luns look like on a day to day basis.  Automation is your friend!  One thing to remember if you are considering purchasing an new EMC array – It is much easier to implement FAST Sublun tiering from the start instead of after you have the array in place.  Existing raid groups have to be migrated to storage pools before sublun tiering can be used.  So if you don’t have available drives to move things around the process could be more expensive or impossible.

Probably even more of a game changer than sublun tiering is the release of FAST Cache.  With FAST Cache you can now add gobbs of EFD based frontend cache to your storage array – up to 2TB depending on the array.  Now before you get too excited about 2TB of cache remember someone has to pay for that much EFD space and it ain’t cheap.  Not to mention that that capability only exists on a CX4-960 which alone cost more than most of our houses.  Even so, adding as little as 73GB of EFD cache can really improve the performance across ALL of your luns.  Even better yet you can select which luns selectively take advantage of this feature with a simple check box.  On smaller arrays like the CX4-120 this feature certainly gives you the most bang for your buck and is really pretty inexpensive.  Here is a chart that shows the minimum and maximum FAST cache configuration for EMC arrays:

Leave Your Laptop At Home

August 1, 2010

Since I don’t have anything earth shattering to blog about this week I guess I’ll fall back to old reliable……iPad blogs! In particular because I’m sitting in an airport writing this blog from mine right now. Over the past few months I’ve been trying to take my laptop with me less and less to appointments. Let’s face it, it’s heavy, it boots up slower than I’d like most of the time, most of the time I can’t find open wireless to get online, and most importantly I usually don’t even end up using it.  Despite all of this I still would find myself hauling the stupid thing around with me all day like a security blanket. Well I finally took some time out of my day and solved my problem. 

The solution……..leave the laptop at home in my office and enable remote connectivity through my home router. Ok, so it’s not a cure for cancer but it definitely makes my life easier. Best of all it’s easy to setup and free. You’ll need a couple of things to get everything working. First, you’ll need a home router that allows you to do port forwarding. If your router was made in the past few years chances are your good to go. On Linksys routers you’ll find it under the Games and Application settings. From here just forward port 3389 through from the outside world to you laptop ip address. 

The second thing you’ll need to make all this work is a way to hit your home system from the Internet. If you have a static ip from your provider then this is not a problem, but for most of us we are dynamically assigned an ip address from our service provider. Of course the issue here is that you public ip address will change every so often. To get around this you’ll need to use a service that provides dynamic dns. Linksys has one you can subscribe to for around $25 per year or you can use a free service from  Once your signed up and have your account credentials configured in your router you are off and running. Now when your ip address changes it is automatically updated to your new dyndns name. So now all you have to do is point you rdp client to your dns address, like or whatever you came up with. 

For me I just use my WYSE Pocket Cloud client on the iPad to connect either via wireless or cellular 3G and it works like a champ. Even with non-3G connectivity it is still quite usable. So now if I need to “get on my laptop” to access local files or download large files it just takes a second to connect from my iPad and its just like I’m sitting at my desk. So if you’re tired of dragging your bulky laptop around with you give this a try.  Works for me anyway.