Sometimes Atoms Are Faster Than Bits

Even though it seems a bit old fashioned sending data from one place to another on physical media, like a USB hard drive or tape cart, can be a lot faster than your wide area network. To point this out, one of my early mentors used to say "Never underestimate the bandwidth of a truck full of tapes."  Announcements last week from Compellent and Amazon point this out as each adds the option of using USB hard drives to load data at a remote location.

In addition to reminding us that atoms can be faster than bits, these two offerings also point out the fact that it takes a significantly bigger, and more expensive, WAN link to upload the existing data to a cloud application or to initially copy a dataset to a DR site than it does to keep the application or replicate the changes to the data.  This is, of course, especially true for the kind of inactive or archive data to which cloud storage is so well suited.

Amazon will now let users send their data on USB, or preferably eSATA, hard drives and have it loaded onto their S3 space by Amazon's data center folks. The page that describes the offering here includes a table that shows how long it would take to upload 1TB of data across various speed connections.  Note that sending that terabyte over a T-1 line would take 82 days. They charge for attaching your drive and for each hour it takes to copy the data from your portable drive to the service, but according to the calculator they provide here, it's usually less than the bandwidth charges for loading it on line. Many online backup providers offer similar hard drive based seeding options.

Compellent's Portable Volume feature uses 1.5 or 2TB USB hard drives to carry the initial copy of volumes that are being replicated between Storage Center arrays.  Since most organizations don't want to pay any more than they have to for connectivity to their DR sites, I've come up with several inventive ways to get the data seeded at client DR sites. The most common being to setup the DR site array at the primary site, seed it and then reinstall it at the DR site.  

Portable Volumes are much easier and allow seeding of new disk volumes once the DR array is established. They can even be used in conjunction with Compellent's snapshots to bring the remote site up date after a WAN outage or data reorganization has created too much change data for the WAN link to handle.The software for Portable Volume in included in version 5 of Compellent's Storage Center software but it will only work with drives purchased from Compellent at $1250 a pair, including a padded Pelikan type case.  Data written to the portable drives is encrypted, and drives aren't locked to a particular array, so Compellent's resellers can (and should) buy a set and then use them to help their customers get replication established or repaired.

While I'd like to see something faster than USB 2 drives as the media, I love the integration of portable storage media and replication that Portable Volume represents.  Once again, Compellent's first out of the gate with a feature that makes the poor admin's job easier. For those who care if it takes 24 hours to copy 1TB of data to a tape, ship it Fedex and restore the data that's the equivalent of over 11.5MB/s.  So a whole truckload...