Fun with Microsoft's iSCSI Software Initiator Versions

Eariler today, doing some demo prep work. Part of the show includes Windows LUN expansions thru SnapDrive 5.0 for Windows Server 2003 SP2. Never got around to updating my Microsoft iSCSI Software Initator from 2.04 to 2.06.

Well, well, well...

Come to find out, Logical Disk Manager Administrative Service unexpectedly terminated. Then there's SnapDrive Vdisk "Service execution status" errors in the debug logs (HRESULT 0x1).

Interestingly, the actual ExpandVirtualDisk operation works in MS iSCSI init 2.04 -- you see the volume size increase. The only user-level issue is a little popup error.

Apparently, it's the last step before refreshing VDS. Users can take advantage of the extra LUN space, but dmadmin.exe (Logical Disk Mgr Admin Service) goes south (access violation) and VDS is now in an "incorrect" state -- funkytown !! FYI -- VDS error is: "Unexpected provider failure. Restarting the service may fix the problem. Error code: 80042420@0200003".

Also of interest -- I don't recall this problem under Service Pack 1 of 2k3. My hunch is new and/or reworked code under VDS and Service Pack 2.

Bottom-line: Your best bet is to ensure your SCSIport.sys (for iSCSI) is up-to-date (2.06) w/ SnapDrive 5.0.

Slinky 2.0 (or, Adaptive Storage Networking in a 10 Gigabit Ethernet World)

It's Slinky, it's Slinky, for fun it's a wonderful stack. It's Slinky, it's Slinky, it's fun for an ACK and a NAK!

Between FAST '08 and this week's launch of Windows Server 2008, I've been thinking a lot about self-tuning performance/scalability of storage networking stacks -- especially with the (eventual) adoption of 10 Gigabit Ethernet in data centers.

For example, the (new) Next Generation TCP/IP stack -- or "tcpip.sys" in Windows Server 2008 -- renders several (older) Windows Registry settings obsolete.

Same is true for Brocade's Fabric OS 6.0 and their whole Data Center Fabric (DCF) initiative: Being able to identify I/O patterns, QoS volumes, and perform traffic isolation are all necessary to simplify storage management.

Also recently discovered an interesting research paper (from NetApp's R&D unit, ATG):

http://hssl.cs.jhu.edu/~randal/papers/batsakis_lsf07.pdf

Storage I/O stacks have lots of growth potential over the next decade -- at the host layer, within the fabric, as well as the storage array itself.

Stay tuned for my continuing deep-dive discussion on this topic!

NetApp: Free Cash Flow King

I'm not a finance geek, but find lots of interesting parallels between IT technobabble ("geekspeak") and finance jargon.

Anyhow, fairly detailed analysis of NTAP's valuation, as well as crunching P/E ratios, net margins, free cash flow, etc. Big takeaway here is a great story for investors, as well as IT managers looking for their next storage system.

See it all here:

http://seekingalpha.com/article/64605-network-appliance-cash-is-king

Bottom-line: Rewards outweigh the risks for NTAP.