FileSlinger™ Backup Reminder 8-27-04: Why Network Backup is Faster

Dear FileSlinger™ clients, colleagues, and friends:

One of the more tech-savvy readers of this newsletter asked me a question after last week's post about network backups (slightly edited):

"How can network backups to another computer be faster than Firewire or USB2 backups to an external hard drive if network speeds are 100 MB/second, Firewire is 400 MB/second and USB2 is 480 MB/second? The numbers don't add up."

So I asked the Ur-Guru. After all, the network backup he'd performed had looked pretty fast to me—faster than my own backups via Firewire to my pocket-sized XHD—but I didn't know exactly how that could be.

This was the answer (slightly edited):

"What Steve says is correct. However, Firewire and USB disks are usually slow and the slowness of the disks is the bottleneck. Ergo, you have a 400 MB/second pipe but the disk will only write (save) the data at 200-300 MB/s. Over a network the higher speed IDEs (connectors normally used for drives inside your computer) in computers will often run faster than the xHD ones."

And, to provide us with a bit of perspective and a telling point:

"In my case when I talk to you about backup over the network I'm running it to machines one a 1000 MB/s link where the disks on the other end will easily handle a 400 MB/s full sustained transfer... that is by far faster than any xHD or USB/FW device.... but that is not the common setup."

(It's not common because a 1 GB/s network is amazingly expensive to install and difficult to find cables for, and most people who aren't Ur-Gurus don't need it anyway.)

"A network backup (100 MB and up) is faster than a CD-R or DVD-R in most cases."

(Certainly it's faster than my DVD-writer, which is an external Firewire device and can only handle DVD-RWs at 1x, which is slow enough to notice.)

"A gigabit (that's 1000 MB) network will by definition be almost as fast as local IDE disks but not as fast as local SCSI arrays (just to complicate the discussion). :-)"

(For the record, SCSI is another means of connecting drives either inside or outside your computer—very fast and generally very expensive, though it's one of our oldest technologies.)

And for those Windows XP users out there: it's a good idea to make a full system backup before installing Service Pack 2, just in case it causes more problems than it solves. (Mac users, you can gloat. For now.)

More backup news next week,
Sallie

FileSlinger™ Backup Reminder 8-20-04: Network Backups

Dear FileSlinger clients, colleagues, and friends:

It's that time again—time to protect your data against the inevitable computer disaster. And it is pretty much inevitable. Drive failure seems to be on the increase and often occurs at about the two-year mark, but might happen even sooner, depending on everything from the manufacturer to whether it gets adequate cooling. If you're really lucky, a hard drive might last you 5 or 6 years.

The other night I got to watch the Ur-Guru making a network backup of a client's laptop in order to reformat the drive. The simple version of how this works is:

1. Plug the computer to be backed up into your network. (This machine had a built-in network port, so that was easy.)
2. Designate a network drive on which to back up the machine. (Windows calls this "mapping" the drive.) This actually took some special utilities because the backup program we were using, Norton Ghost, works outside the Windows environment.
3. Run your drive-mirroring software.

Presto: a copy of computer one stored on computer two.

Transferring data over a network is much faster than writing it to a CD or to a USB or even Firewire drive. It can also spare you having to get an external drive, as long as you have more than one machine on your network and the machine you want to put your backups on has lots of extra hard drive space.

It is possible that every machine on a network could go down at one time (fire, flood, earthquake, etc), just as it's possible that both your computer and your external drive could be destroyed at the same time. But it's not nearly as likely that two computers will die simultaneously as that one drive will fail when another is fine.

There can be some tricky bits involved in setting up network backups, depending on your hardware, and a Ghost backup won't work over a wireless network. (Wireless networks are much slower than cable networks anyway, even if you don't notice this in your day-to-day e-mail and web browsing.) But they can still be a good option for anyone who already has a home or office network set up.

More backup news next week,
Sallie

FileSlinger™ Backup Reminder 8-13-04

Dear FileSlinger clients, colleagues, and friends:

It's that time again—get out the disks or hook up the external hard drive and make your backups.

I have to hurry out of town this morning and don't have any exciting backup-related news and advice, but didn't want to leave you without your reminder to protect your hard-earned data against crashes and other disasters.

More news next week from your backup station,
Sallie

FileSlinger™ Backup Reminder 8-6-04: RAID and Redundancy

Dear FileSlinger clients, colleagues, and friends:

Last week I got to go on a tour of a data center—a place designed to house huge arrays of servers securely.

I went on this tour because I wanted to know more about how ASPextra.net, the data center's largest client, works. The concept of an ASP (Application Service Provider) interested me when I first heard of it. When you use an ASP, instead of buying all the extra hardware and software and installing and maintaining it yourself—and then having to worry about things like synchronizing your home, laptop, and office e-mail and other data—you 'rent' all those things from an Application Service Provider. This is not necessarily inexpensive, but can potentially pay off over time for small businesses and particularly for people who travel a lot. (To find out more about ASPs in general, see the excellent article by How Stuff Works.)

But before I started recommending ASPextra.net (that's their web address as well as their name) to clients, I wanted to find out whether they were really providing the kind of security and ease of use that they claimed. And, naturally, I was hunting for information on the subject of backups.

So there we were down at ColoServe in San Francisco. In addition to needing to hand over my driver's license in exhange for a pass to get in, I certainly saw plenty of evidence of physical security: the computers are in locked cabinets in locked rooms, the building has its own generator to provide power in case of rolling blackouts and an advanced fire control system, not to mention the air conditioning that comes up through grids in the floor to keep disks from overheating.

Why is air conditioning part of server safety? An overheated disk or processor is more likely to fail—if your computer gets too hot, it will crash. Don't ignore cooling fan error signals, and make sure you dust the vent at the back (or bottom, with most laptops) of your machine frequently.

Then there's security in the sense of having a network connection that's always on: the "pipes" bringing data to the entire West Coast runs directly underneath the data center, meaning that for anything to interrupt internet service to ASPextra's servers, it would have to be something that would take down the net for the whole state. There were redunant network cables on all the machines, so in case one failed, information would keep flowing.

We also got a demonstration of how the ASPextra spam and virus filtering system works to keep most viruses and spam from ever reaching their clients' computers. It all looked pretty solid.

But backups, I said. How did they handle backing up their clients' data (and software)?

The answer was "Actually, we typically use a RAID system on the client servers with dual or sometimes quad internal HDs. If the client wants a dedicated backup server, that is no problem, but that does cost extra."

I've heard the term RAID a million times, but I had to go look it up in the Webopedia to be sure what that meant. RAID stands for Redundant Array of Independent Disks. There's that word "redundancy" again. While it's something you want to avoid in your writing, redundancy is something you want to achieve when it comes to your data. It's like carrying a spare tire.

In a RAID, if one disk fails, another can replace it, thanks to "disk mirroring"—in this case not quite the same thing as the disk imaging done by programs like Norton Ghost, because the duplicate information is written simultaneously, all the time. (Incidentally, buying your own RAID would run you anywhere from about $2500 to $20,000, according to a C|NET search.)

Asked what the failure rate of the disks was, our guide said that only one disk had failed in 15 months. For drives in constant use, that's an impressively low failure rate. The Ur-Guru (who was on the tour with me) has had many more disks than that fail in the past two years—probably due to inadequate cooling.

If you consider an ASP, make sure they can provide all of that. In the meantime, keep your computers cool and keep backing up your data.

Until next week,
Sallie