Qualcomm Mirasol Display

Keep an eye on this tech:  Qualcomm Mirasol Display

iPads are awesome.  I love the OS and the video is great for playing games & watching movies.  However, as an e-reader, the Kindle is better.

The Amazone Kindle has the best display for reading, but its operating system is not so great for web browsing and add-on apps.

What I'd really like is a color Kindle screen on the iPad.

This tech might provide that.

Addendum: 2011-04-18

Apple Insider reports on a patent filed by Apple that may solve my text reading complaint. The patent involves layering an e-ink display over the top of the typical color display; the operating system dynamically figures out which one to use for the data displayed. More info here: http://www.appleinsider.com/articles/11/04/07/apple_exploring_hybrid_e_ink_lcd_displays_with_independent_regions.html

SQLServerpedia

http://sqlserverpedia.com/

Run by Quest Software, this site is a Wikipedia-style collection of SQL articles.

Concerns about multi-subnet failover clustering

According to Microsoft’s Denali books online, a multi subnet failover cluster is a cluster in which each node of the cluster can be located in different subnets.  In my case, I want a two node active/passive failover cluster, with each node in a different geographic location.  This is known as a stretch cluster.  Reading through Microsoft’s documentation, I noticed this point:

As there is no shared storage that all the nodes can access, data should be replicated between the data storage on the multiple subnets.

In our previous implementation, we replicated the data between the two locations using an EMC-based hardware mirror at the SAN level.  I was naively hoping that Microsoft's implementation would own the replication when I read the statement that followed:

With data replication, there is more than one copy of the data available. Therefore, a multi-subnet failover cluster provides a disaster recovery solution in addition to high availability.

After reading through various documents, I get the impression that Microsoft still expects us to use third party technology to replicate the data between the sites.  For example, the graphic displayed by this guy shows "SAN Replication".  For now, I guess we will continue to use EMC's SAN-level replication.  It might be worth checking into SteelEye -- at last year's TechEd conference, a Microsoft rep pointed me in their direction for a software-based mechanism that could do the necessary replication.  Oh well, at least our network guys will be happy about doing away with the stretch VLAN.

Other thoughts about multi-site clustering --

A few paragraphs later, Books Online gives as an example exactly what we plan to do:

SQL Server failover cluster SQLCLUST1 includes Node1and Node2. Node1 is connected to Subnet1. Node2 is connected to Subnet2. SQL Server sees this configuration as a multi-subnet cluster and sets the IP address resource dependency to OR.

This bit about setting the IP address resource dependency to OR is rather intriguing and points to one of the changes in SQL 2012.  It seems that the IP addresses are not owned by all the nodes in the failover cluster.  The IP address resource dependency can be set to either “OR” or “AND”.  Books online offers several examples where we would use “OR” as well as an example when we would use “AND”.  Of particular interest is the following example consistent of THREE nodes:

SQL Server failover cluster SQLCLUST1 includes Node1, Node2, and Node3. Node1 and Node2 are connected to Subnet1. Node 3 is connected to Subnet2. SQL Server sees this configuration as a multi-subnet cluster and sets the IP address resource dependency to OR. Because Node1 and Node2 are on the same subnet, this configuration provides additional local high availability.

This example raises another concern – that of DNS latency issues.  In the example above, recall that both nodes 1 and 2 are in the same subnet; node 3 is on a different subnet.  If SQL fails over to node 3, a DNS record must be updated to point to the new IP address on node 3.  Books online indicates that this could be a problem if we have multiple DNS servers (think DNS synchronization issues).  My real concern is this statement:

The SQL Server cluster will not come online on Node3 until the DNS synchronization is complete.

So I guess this is why some shops choose to go with three nodes in a cluster instead of our typical two.  It's something that I will have to consider going forward.

One other concern – be aware that multi-subnet failover clusters are only supported on SQL Datacenter, Enterprise, Developer, and Evaluation editions.  Notice what is missing – Standard (and Workgroup).  Bummer.

SQL 2012 - Books online

Books online for Denali (SQL 2012) can be found here:

http://msdn.microsoft.com/en-us/library/ms130214%28v=sql.110%29.aspx

Incidentally, any recommendations for a good e-reader?  I would like to use a tablet-style reader to view Microsoft's books online.  Given my collection of iOS devices, an iPad is the obvious first option but I am concerned about eye fatigue with the iPad's glossy screen.  I previously had an original iPad and - while I loved the device - I was never convinced it was a good e-reader.

Amazon's "E Ink" screen could solve the eye fatigue problem but I don't know how well the Kindle's "experimental" web browser would process Microsoft's books online.

And no, reading off the computer screen is not appealing in this case - neck strain, eye fatigue.  I want to use my bifocals and read this like a book!

Suggestions?

Why is multi-subnet failover clustering important?

My network team did not like the way SQL 2008 R2 and previous versions of SQL handled failover clustering.  We were comfortable with setting up active/passive failover clusters and were attempting to place a second node in a disaster recovery site located half a mile or so away from our primary.  By mirroring the SAN storage, we had a good way to set up a simple active/passive failover cluster that would be usable in case of a disaster.

However, previous versions of SQL did not support setting up the second node in a subnet different than the first.  We could still set up a second node in the DR site by extending the subnet between the two physical locations, but this was a work-around -- not ideal according to our network engineers.  It required stretching a V-LAN across locations to expose a single IP address across the two sites.

The key feature that was missing was multi-subnet failover clustering.  With Denali's multi-subnet failover clustering, we can now configure SQL Server failover clusters across multiple sites to create stretch clusters without implementing stretch V-LAN technology.

This is why I am so excited to see this feature in SQL 2012.  In future posts, I will investigate to see if this feature solves our problem.

Geekstorm.net

My old website --

http://geekstorm.net/stuff.html

At Geekstorm you will find a list of stuff that I find useful. Utilities, apps, product recommendations, and the like.

SQL 2011 - What's new?

Currently studying the next version of SQL code named Denali.  Potential release date in July of 2011, so I'll call this SQL 2011. (Edit: It was delayed and is called 2012....)

What's new?

• Contained databases - This is supposed to make it easier to move databases between servers
• HADRON - New High Availability & Disaster Recovery options
• Support for Server Core - Look ma, no GUI!
• A bunch of changes in SSMS that I don't really understand yet
• Column-based query accelerator
• Multi-Subnet Clustering
• Itanium no longer supported

These are just the highlights.  I'll drill into each one of them (plus much, much more) in the following posts.

Hello World

Over the years, I found the best way for me to grok a new technology was to leave myself a trail of bread crumbs.  I need to play with it, read about it, immerse myself in it, and write about it.  Many moons ago, I used to make my notes in HTML with notepad or vim.  Maybe this Blog interface will be easier... by making notes here, I hope to leave a virtual path that I can later follow to re-learn those things that I forgot.  Theseus had a ball of string.  Hansel had bread crumbs.  These are mine...