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Why isn't all storage in a SAN?

By Charles Vallhonrat

Despite many years of strong growth in storage migrating to SANs, we still live in a world where a huge amount of storage is still directly attached to servers.  Why have we not seen all storage move external for any environment with multiple servers?  Surely the SAN offers lower cost, higher data protection, and better utilization.

The fact of the matter is a lot of data remains inside servers or directly attached via a JBOD because that is the best place for it.  Maybe there is a specific performance need, or certain local control of data and access that leads to customers keep storage directly attached. Customers are savvy and until the SAN offers a better solution for their specific need, they are keeping certain storage infrastructure close to the server.

Enter shared SAS.  It looks and smells like shared storage yet offers the simplicity of Direct Attached Storage (DAS) and has no requirement for a switch or to manage a network in smaller configurations.  HP introduced a shared SAS solution - The MSA2000sa - in August 2008 and quickly SAS became 25% of the interconnect mix for MSA.  Now with the release of a generation 2 model (or G2) there are a number of improvements that will likely boost usage still further.  The G2 products is faster than the previous generation, supports more drives, supports more snapshots, supports more LUNs, supports more servers...and on and on.  But, one of the most important new features is support for 2.5" inch (aka Small Form Factor) drives.  Yep, the same type of drives used in many ProLiant servers.  In fact, with the MSA2000sa G2, the small form factor drives are same drives that are used in our HP ProLiant servers.  Talk about keeping the simplicity of DAS...

By the way, once customers get the benefit of shared storage using SAS, the MSA architecture allows them to upgrade controllers to iSCSI or Fibre Channel if they wish.  Maybe we have finally found the catalyst to remove storage from servers.

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HP BladeSystem and StorageWorks Synergy

By Lee Johns

I often get asked why HP BladeSystem and StorageWorks are such a compelling combination.  There are multiple reasons and it starts with the cost of connecting to existing fibre channel storage which can be reduced by up to 50% with the reductions in cables, single failure points and administration when you use a technology like HP Virtual Connect.  You of course also benefit from the infrastructure savings you get from implementing blade servers in terms of time, energy, change and cost.  

Today there is a new reason.  Direct connect storage!  Think the simplicity of DAS with the resource sharing of a SAN.  With HP BladeSystem you can now implement up to 192TB of shared storage across 16 blade servers using a simple, but high-performance 3Gb SAS interconnect.  What's more the Storage offers all the management features and capabilities of the HP MSA 2000 but without the requirement to manage a fabric (Fibre Channel or iSCSI).   

Now don't get me wrong.  Fibre Channel and iSCSI storage are every bit as important as they were yesterday with BladeSystem.  In fact HP also announced a technology called Virtual Connect Flex-10 for BladeSystems today that will offer great benefits for future iSCSI storage solutions for our EVA and MSA as well as future products from our acquisition of LeftHand Networks.  The difference today is that if implementing Fibre Channel or iSCSI was not the right choice for me as a customer, I now have an alternative that offers breakthrough simplicity.   Direct connect storage is perfect for Server Administrators who want to implement a simple shared storage environment for boot infrastructure or other server administrator controlled data.  It is ideal for small and medium businesses or remote sites who are looking to implement there first SAN but want a simpler solution.  It is great for VMware infrastructure and supports VMotion. It is great second tier storage for Enterprises.  

Customer excitement in HP early previews has been very strong.  In fact it has so much utility for new implementations or existing SAN environments it make me wonder why the traditional storage only vendors are not offering it.  After all it simply offers customers more choice. 

Lee Johns, Director of Marketing for Entry Storage

Top Ten Reasons Why DAS Will Grow!

By Lee Johns

For a number of years now the relentless growth of SANs has overshadowed the Direct Attached Storage market (DAS). Indeed market studies have shown that while still a large market, DAS is shrinking.  Howeverrecent advances in SAS drives and SAS connectivity, along with market shifts are pointing to a resurgence of DAS. 


I thought I might put forward 10 reasons why over the next 18 months DAS will grow! SO HERE WE GO (drum roll)...


1)    SAS connectivity offers much more functionality that older SCSI cable connections.  Indeed major systems manufacturers, like HP, have introduced SAS connected arrays that can provided a shared storage environment for multiple servers just like a SAN. For smaller environments this offers SAN functionality without the headache of managing a network.


2)    Server Blades are the hotest growth areof the server market. By consolidating servers in a single enclosure, SAS based arrays will in the near future be able to share storage across more servers without using a network with traditional server architectures.


3)    Server Virtualization is the hotest SW growth story in the market.  Using products like VMware forces customers to have to consider how to implement shared storage, and for many using fibre channel storage is too expensive.  SAS connectivity offers a lower cost alternative and is easier to manage, especially for server administrators.  SAS products like the HP MSA 2000sa are VMware certified


4)    Although SAN's have consolidated a huge amount of data there still exists an extraordinary amount of drives in servers today that have not been consolidated for a variety of reasons.  SAS offers a lower cost consolidation play for the drives that have not today been moved to SANs


5)    Ongoing management costs are one of the major issues faced by IT organizations today.  If you don't already have a Fibre Channel SAN and just require shared storage for a few simple applications why look at managing a new fabric and hiring expensive SAN administrators


6)    Applications like Microsoft Exchange are moving more and more storage services inside the application.  They are even recomending DAS for performance. 


7)    Web 2.0 companies are having to think differently about storage implementations b/c of new scale out applications.  They can not afford traditional SAN's and the promise of architecting Storage based on DAS is compelling


8)   Server purchasers can not buy SANs without engaging Storage teams.  They can buy shared SAS storage though and get the same effect


9)    Choice is always important as a consumer.  Products like the HP MSA 2000 offers the choice of Fibre Channel, iSCSI or SAS interconnect, while providing the same basic functionality and management interface. This means you can buy into SAS connected storage with a simple migration path to a future SAN based on iSCSI or Fibre, if you need the future scalability.


10)   AND FINALLY......... COST, COST, COST.  It is an easy way for SMB's to implement shared storage and have you seen the economy lately?!?


What do you think?

Storage Just got SASsy! VMware set free of the SAN.

By Lee Johns, director of marketing, StorageWorks Entry Storage and Storage Blades, HP

Serial Attached SCSI (SAS). Does not sound very exciting really does it? Many of you will know SAS as a class of disk drives found in servers and arrays but how many have ever though of using SAS as an interconnect for storage instead of Fibre Channel or iSCSI? Probably not many and with good reason. SAS is a point to point protocal that can not compete today with the sophistication of network storage toploogies like Fibre Channel and iSCSI for Enterprise Arrays.

But what if you just want to deliver a simple solution for shared boot, or a VMware infrastructure that enables Vmotion without a SAN, or you have an application that performs best with a direct attached storage architecture but you want better storage utilization. Now the cost and complexity of a SAN seems somewhat redundant. Why is there no way to provide the performance you need with the consolidation and utilization of a SAN without the overhead of an expensive fibre channel network infrastructure or leaving things as they are with existing direct attached storage (DAS)?

There is an answer. It is using SAS as a shared storage interconnect and with it you can build much simpler shared storage environments that can be managed by a server administrator. This saves you time, money and enables you to build the best architecture for any application. It is not a replacement for the traditional SAN but it is an enhancement to DAS that places the data and control where it should be and does not force fit a SAN as the answer to all storage problems.

Shared SAS solutions are available today and I encourage you to think where they could help you improve your Direct Attached Storage architectures and augment the SAN. SAS began as an internal server interconnect so maybe it is no surprise that dedicated storage vendors like EMC and NetApp are ignoring SAS as an interconnect. They feel it is threatening to them and that is exactly why you should be taking a serious look!

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  • 25+ years experience around HP Storage. The go-to guy for news and views on all things storage..
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