Stephen Foskett, Pack Rat

ZFS really piques my interest, so I just had to include it in my TechTarget storage virtualization seminar series.

Here’s a quick primer for those of you who aren’t familiar with it, and thus are wondering why anyone would get stoked over a filesystem!

ZFS (originally “zettabyte file system” but now just ZFS) takes the essential technolgy from file systems and volume managers and stirs it together into one important new way to manage storage.  It’s an open source project started and managed by Sun, using the CDDL license (so Richard Stallman wouldn’t approve).  It’s loved by both Sun and Apple which makes it much more important.

See, ZFS will probably replace UFS (on Sun), HFS+ (on Mac), and every other file system and volume management product out there, especially on these platforms.  And I expect to see it appear on Linux once the tricky bits are resolved (which have to do with licensing not technology…)

ZFS creates a truly flexible, extensible, and full-featured pool of storage across systems and disks.  No more (of the old) arcane syntax, commands, ridiculous GUIs (ahem, Sun), and unnatural limitations of old system storage management.  With ZFS, you add some disks, get some space, and use it.  But it gets cooler than that…

ZFS “zpools” (file systems) live on “vdevs” with striping and optional RAID-Z/Z2 (which is double-parity kinda like RAID-6).  And, get this, every block is protected with checksums to ensure that the rapidly rising incidence of disk errors won’t bite you.  Want capacity?  128-bit addresses mean near-infinite space (in theory).  Oh, yeah, and all blocks are “copy-on-write” for snapshots and clones, something that barely works on most desktops and workstations.

But alas, there are some limitations…  Adding (and especially removing) vdevs is hard (read: maybe impossible) depending on how your storage was set up.  Stacked RAID is impossible, so no “Z+Z2″ for you!  And, until Sun integrates Lustre, there is no clustering support.

And then there’s the fact that Sun and Network Appliance are actively suinging each other over the fact that the technology in ZFS has ended up looking an awful lot like their bread and butter super file system, WAFL.

So there you have it.  If you’ll be in Washington DC on March 4, or Durham NC on March 6 and are interested in this topic, and the wider world of storage and server virtualization, I’d love for you to register and attend this free seminar!

When researching the interaction of storage and VMware for my upcoming TechTarget seminar series on storage virtualization, I picked up a few little tidbits of information that I wanted to share…

1. Beware of block sizes greater than 256 KB when using certain Fibre Channel arrays!  VMware’s performance research shows that throughput drops on some FC arrays, though they didn’t specify which ones…  Check out more performance suggestions on the VMware performance blog!
2. Align your virtual disk starting offset to your array.  A simple way to do this is to boot the VM and use diskpart, assuming you’re using Windows.  Misaligned disk offsets can double disk I/O, or halve performance, depending on how you look at it…
3. If you are using shared storage and want virtual disks greater than 256 GB, you must use a VMFS block size larger than 1 MB.  Or you could just use raw device mapping or NFS!
4. If using iSCSI or NFS, use a separate network or VLAN and consider an iSCSI HBA.  These cut down CPU load significantly in high-I/O situations.
5. De-duplication primary storage can have a huge impact on VMDKs created from a template!  See if your array supports this!
6. Thin provisioning can also be very useful in virtual machine storage, since a lot of VMDK space is empty…
7. Consider using NFS instead of FC/iSCSI with VMFS or RDM.  It’s pretty cool what modern NFS servers can do!  See NetApp’s Best Practices doc, for example.

If you’ll be in Washington DC on March 4, or Durham NC on March 6 and are interested in the world of storage and server virtualization, I’d love for you to register and attend this free seminar!

I’ve been feverishly preparing for my upcoming TechTarget seminar series focused on storage virtualization, so I thought it might be interesting to post a few topics from the talk here on the blog.  If you’ll be in Washington DC on March 4, or Durham NC on March 6 and are interested in the world of storage and server virtualization, I’d love for you to register and attend this free seminar!

I’m kicking off with one of my favorite topics, logical volume management on servers. This is the longest-standing and most-successful face of storage virtualization, and the one I was first exposed to. Put simply, volume managers abstract block storage (LUNs, disks, partitions, what have you) into virtual “volumes” for use by the server. They look the same to the OS, and still need a filesystem, but are much more flexible, as we’ll see.

Volume managers are very common today - all modern OSes (except for that one from Apple!) have volume managers built in. Windows has the Logical Disk Manager, which I’m told was co-engineered (or something) with Veritas way back when and which I’ve covered in my Storage Magazine columns. Linux has an implementation of LVM, which I wrote something about way back when, and which has now not been supplanted by EVMS as had once been supposed. AIX it’s own twist on the original LVM, as does HP-UX. Solaris has the variously-named Solstice DiskSuite/Volume Manager which has evolved substantially in the 15 or so years I’ve been using it. And everyone has Symantec’s Veritas Volume Manager/Foundation Suite, which we in “the biz” view with considerable admiration and some skepticism, as is the case with all good front runners!

Folks mostly use volume managers for flexibility. It’s really quite amazing what you can do when your servers run them, enough that you often wonder how you got along without them!

• You can resize volumes (aka file systems or drives) on the fly (if your file system supports this as most modern ones do)
• You can protect data with RAID, even if your storage doesn’t support it (think bare disk drives)
• You can add storage capacity on the fly by concatenating new to old or (maybe) expanding existing stripes and RAID sets
• You can mirror volumes, create snapshots, and even replicate data to remote locations (this functionality varies by product, of course)
• One of the most powerful things (to me) was the ability to migrate live volumes from one storage device to another when making infrastructure changes

In short, volume management = server-based storage virtualization! So even if you were skeptical about the claims about storage virtualization, you might already be using it! Amazingly, a good volume manager can do anything a storage virtualization appliance or enterprise storage array can do. In fact, some virtualization appliances have more than a little volume management source code in them…

And the only cost for all this great stuff is the impact on your server’s CPU, memory, bus, access control, etc…

The chart below compares the major volume managers, and includes a little easter egg at the bottom… But we’ll cover that on another day.

There is a total lunar eclipse beginning right now, viewable across the United States and Europe!  The moon will be fully eclipsed an hour and 15 minutes from now, midnight my time.  So go outside and look up!

Apple’s business customers do not appear amused at the company’s exit from the enterprise storage space, but it was the quiet way that the company dumped the Xserve RAID product from their lineup that really irked. “XRAID” customers were left wondering whether they made the right choice, and if the company’s support for the defunct storage array might dry up, too.

Apple pulled the plug in typical fashion on February 19, closing the online Apple store down and reopening without an announcement. Users were greeted by cheaper and expanded iPod Shuffles and a new rev of the Xsan SAN filesystem product. It was quickly noted that the latter now supported third-party Fibre Channel storage arrays, but little mention was made of Apple’s own FC array product, the Xserve RAID.

It turns out that there was a reason for the oversight. Visitors to the former home of the product on Apple’s web site were greeted instead with a splash page pointing them to Promise Technology’s VTrak E-Class array, and all documentation for Xsan 2 prominently features the Promise array. Users fumed, bloggers blogged, and Apple said nothing about the demise of their product.

Gizmodo finally teased something like an official statement from Apple later in the day. Apple’s Anuj Nayar admitted that the product was no more, and claimed the company would still sell drive modules “while supplies last.” SearchStorage.com got a much more official-sounding answer, but it remains the same: Xserve RAID is gone.
Users were having none of this. Although the Xserve RAID was outdated, with PATA disks and 2 Gb Fibre Channel, most expected a refresh. And they voiced exasperation with Apple’s quiet retirement and less-than-strong statements of continuing support for existing customers. A few users suggested stocking up on spares, while others defended Apple’s cutting off of a “non-core” product line.

At the end of the day, it does seem to be in Apple’s best interest to allow third parties to handle RAID array development and sales, as TidBITS points out. But it would have been a wiser choice to handle their often fanatical customers with more concern and forthrightness. At the very least, the company should issue a statement about the demise of the product and their continued support for existing customers.

I love Google Reader. I love Friendfeed. I even like Plaxo Pulse. But here’s what I want: A one-stop blog aggregator that lets me do everything for everywhere in one place. I want integrated socialization, and especially threading and integrated commenting. And I think we can do it! Read on for a recipe for the perfect blog aggregator!

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Apple has an odd relationship with enterprise computing. Their Xserve server products are strong, as is Leopard Server, and they have an excellent SAN file system, Xsan, that they just updated. Yet, Mac OS X is the last major operating system with no volume manager (thanks to the antiquated HFS+), and it looks like the company EOLed their Fibre Channel RAID product, Xserve RAID, today.

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TechTarget recently announced a new Storage Decisions Seminar series focused on Storage Virtualization, with yours truly as the speaker!

Although the content is still being formalized, the first sessions are right around the corner on March 4 (in Wachington, DC), and March 6 (in Durham, NC). If you’re near either of these cities, I would love to have you attend and say hello! It’s a free day-long seminar with lots of technical and business content.

Further dates will follow in June, July, and later. I’ll be in London in November, too!

I’ll post more details as they become available!

Ever since I upped my iPhone to version 1.1.3, I’ve been puzzled by the allocation of a couple hundred megabytes of capacity to “Other”.  Look at the picture here - notice that it has 243.9 MB of “Other”?  Some of that is my custom ringtones (self-created thanks to AtomicParsley!), but not much.  The rest magically appeared when I updated the phone from 1.1.2 to 1.1.3.  The other iPhone in my family has the same mysterious space gobbler, but the number is slightly different.

So what is taking up this space?  Other people have noticed the issue as well, and no one’s figured out just why it happened.  Some have suggested it might be email, webclips, notes, etc, but this doesn’t explain why it jumped after the upgrade.

My theory is that it is a backup of the operating system.  Since the download was 165 MB, it seems to me that Apple might be keeping a spare copy of the whole thing on the phone as a backup (or something).  Perhaps it was supposed to be deleted after the upgrade and wasn’t? Or perhaps it’s something like TiVo’s “amusing” OS image card trick?

TechTarget’s Storage Decisions shows have long been a highlight of the data storage industry calendar, and the company recently announced the dates for 2008. I’m pleased to announce that I will again be presenting at these shows, and will post more details on my topics as they become available.

Storage Decisions 2008 dates and locations:

• Chicago, May 13-15
• Toronto, June 5-6
• New York, September 23-25
• San Francisco, November 4-6

The format is being tweaked this year (as has the editorial direction of Storage Magazine) to include more in-depth technical content, and I’m sure the show will remain excellent. If you haven’t been, you’ve missed out - there are no product vendors on stage or even in the sessions, so it’s very focused on real-world users of storage technologies, and the sessions have always been top notch!