Network Computing is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

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.

  • 1