Stephen Foskett, Pack Rat

This is part of an ongoing series of longer articles I will be posting every Sunday as part of an experiment in offering more in-depth content.

Although many discussions in the storage industry focus on the relative merits of one protocol or another, the conversation occasionally turns to the core issue at hand: We continue to patch together a system based on outdated concepts. Most storage protocols continue to mimic direct attached storage, and most of our so-called networks act as point to point channels. An ultra-modern virtualized storage infrastructure with all the latest bells and whistles still holds the concepts of block and file at its core. Whenever the storage industry has tried to bring about real storage management they have been stymied by a lack of context for data.

No amount of virtualization, and no new protocol, will fix this. Put simply, we need a storage revolution. Continue Reading »

This is part of an ongoing series of longer articles I will be posting every Sunday as part of an experiment in offering more in-depth content.

I am not the typical enterprise storage user. In fact, I am not an enterprise storage user at all - I am a consultant focused for over a decade on assisting enterprises with their storage architecture and strategy, working with businesses of all sizes. My background is both a blessing and a curse - I have seen far more enterprise storage environments in much more detail than most people, but I am unable to truly empathize with my corporate storage compatriots since it’s not really my gear and data that I am working with.

Based on this experience, what does the future hold? Where is enterprise storage heading? Read on for my thoughts.

Continue Reading »

One of the new features in Xen 3.3, released this week, caught my eye: Paravirtualized SCSI (PVSCSI), which allows a guest OS to directly interact with a SCSI (or Fibre Channel) HBA. This should allow more specialized applications to be virtualized in Xen environments that use SCSI or FC storage without requiring the addition of a dedicated physical storage port per guest.

PVSCSI gives virtual machines direct access to SCSI and FC HBAs, and plays nicely with NPIV (Xensummit diagram by Fujitsu)

Functionally similar to VMware’s Physical Compatibility Mode for Raw Device Mode (RDM) volumes, PVSCSI enables certain applications that require direct SCSI communication to function in a virtual environment. Examples include Oracle RMAN, backup applications, and potentially SAN management software.

PVSCSI plays nicely with N_Port ID Virtualization (NPIV), too, so you don’t need to assign a physical HBA port to each guest - they can all share a port or two, and each would have his own N_Port on the Fibre Channel fabric.

In their Xensummit presentation about PVSCSI, Fujitsu showed impressive performance numbers, demonstrating that the technology doesn’t cause much of a performance hit even though it is substantially more complicated than the alternative approaches. I do wonder how PVSCSI managed to outperform Dom0 with 128k writes, but let’s chalk that up to insignificant variations in timing…

Now if only Xen would update the (3.2-era) readme files on their download page!

VMware just released Update 2 for VMware ESX Server 3.5 (Virtual Infrastructure), and it includes some storage fixes of note:

1. Support for Volume Shadow Copy Service (VSS) for filesystems Windows Server 2003 and Windows Server 2008 guests.  This means VMware services like VCB and SRM can now signal Windows Server to quiesce filesystems before creating a clone or snapshot and is a major addition!
2. Windows Server 2003 guests also get application quiescing, where supported.
3. You can now extend a live, running VMFS volume as storage is added, just like Windows Vista and 2008 guests could already do with raw device mode (RDM).  Note that this only works for flat disks with no persistent snapshots open.

Continue Reading »

I had two great storage virtualization seminars this week, in New York and Philadelphia.  As usual, audience participation was key, and interest in VMware and Hyper-V remains high.

One of the main questions I always get is which protocol one should use for VMware storage. My recommendation remains that the answer is an organizational one more than a technical one.  There are certainly performance, CPU utilization, and support differences between Fibre Channel, SCSI, iSCSI, and NFS on VMware, all of these can work fine in many situations.  Although this is addressed in my presentation, I thought it wise to point out some of my sources and (concurring) opinions.

First, I point you to the official VMware VI Team blog, where they reiterate that VMware is protocol-agnostic.  They commit to support all storage protocols equally, and promise to add missing support as soon as possible.  See especially their table of support, which shows that iSCSI currently can’t be used for clustering (!), among other insights.

I’d also like to point out three sources for my seminar slides:

• VMware’s Comparison of Storage Protocol Performance paper, which pits Fibre Channel against hardware iSCSI, software iSCSI, and NFS.
• VMware’s Performance Characterization of VMFS and RDM Using a SAN, which shows that there is a negligible performance difference between shared storage and the two varieties of RDM.
• NetApp’s NetApp and VMware Virtual Infrastructure 3 Storage Best Practices (recently updated), which is a wealth of information on shared storage with NFS, even if you’re not a NetApp customer.

TechTarget recently uploaded three podcast versions of my SAN School series from Storage Decisions last year.  These are audio-only, but I might be able to dig up the accompanying slides.  If you’re interested in this, please leave a note below or contact me through email.

So without further ado, I present three lessons on SAN storage:

• SAN School Lesson One: Building a SAN - In this first lesson of SAN School, I discuss the different types of storage arrays, switches, and software that make up a storage network.
• SAN School Lesson Two: SAN Architecture and Topology - In lesson two, I discuss the evolution of SANs from standalone entities, to islands and beyond. Discover techniques that can make a substantial difference in the way data is moved and processed, as well as in your company’s consolidation plans.
• SAN School Lesson Three: SAN Management and Security - In this Podcast, I explain what the options are for management tools. I cover array management, change management, virtualization and more to help you manage your environment. 

Real Video: Where the SAN Stands

Curious about the current state of SAN technology?  Stephen Bigelow of TechTarget interviewed me (last summer) about SAN options, and the video is now live on their BitPipe site.

Topics covered include combined iSCSI and FC SANs, ups and downs of modular storage and oversubscribed switches, next-generation SAN management applications, storage virtualization, and best practices for SAN design.

Here’s a snip - the three best practices for SAN design are as follows:

1. Choose reliable high-quality hardware
2. Build dual redundant networks
3. Protect management interfaces

Watch the whole video (it’s 17 minutes long) and let me know what you think!

Even though storage virtualization technologies have been on the market for 20 years or more, and numerous companies have tried to sell it as a product in its own right for at least half that long, many are still unsure of what to do with the technology.  A great new piece by Dave Raffo, News Director at SearchStorage.com, discusses the wide variety of virtualization solutions and the real impact they can have.

Dave called me for this piece, and I was pleased with the question.  Truth be told, there really are compelling benefits from virtualization, but most folks have been waiting for a real “must have” killer application for the technology.  In order for this tech to make the impact it should, we in the industry have to change some of our thinking:

• Storage virtualization means more than just Fibre Channel block aggregation.  There are great applications inside servers and arrays and in the NAS world, too.
• Speaking of NAS, Microsoft DFS is probably the most-implemented storage virtualization product, and just about every NAS array has cool aggregation and migration features.
• Virtualization is a feature, not a product.  HDS has seen the amazing potential for block virtualization in migration and storage flexibility, and this is just the tip of the iceberg.
• Storage and server virtualization go well together - so well, in fact, that ESG reports that 24% of those who have implemented the latter are also using the former!

Fibre Channel over Ethernet (FCoE) has been a hot topic of discussion in the enterprise storage world lately, but many end users are just now hearing about it.  Although some folks seem to think it’s here with a vengance, others doubt that it will ever make the splash it promises, with 8 Gb FC, iSCSI, and even AoE (ATA over Ethernet) showing more promise.  There has been some back and forth, and even a little backpedaling.

What do you think?  If you’re a Plaxo user, I created a poll over there to see if folks think it will rise, and when.