Storage

Using DVD-RAM for network storage

In this Daily Drill Down, Brien Posey discusses why DVD-RAM might be a good network backup option. He also candidly discusses his blunders setting up new DVD-RAM drives in Windows 2000. His errors may save you from yours!


Practically everyone uses magnetic media, such as tapes, for their nightly backups. It’s possible, however, to use DVD-RAM. In this Daily Drill Down, I’ll explain why DVD-RAM was the best choice for me. I’ll also cover the hardware and software required for using DVD-RAM, troubleshooting, and data storage techniques.

What’s DVD-RAM?
Just as a CD-RW drive can write and rewrite data to a CD, a DVD-RAM drive can write and rewrite data to a DVD. In addition, a DVD-RAM drive can read data from both CDs and DVDs. If the idea of writing to DVDs sounds good, don’t get too excited yet. DVD-RAM media is great for data, but it’s impractical for duplicating DVD movies. First, it’s impossible to read a DVD-RAM disk in a conventional DVD player. Secondly, there’s no software capable of reproducing DVD movie format. Finally, since blank DVD-RAM media costs about fifty dollars and most DVD movies only cost about thirty dollars, it’s actually cheaper to buy a movie than to bootleg it. So let’s talk about data storage.

Why I use DVD-RAM for backups
Recently, I decided to replace my main file server. At the same time, I reevaluated my backup solution. Previously, I had been using a tape backup. Although my nightly backups were set to run automatically, I was having trouble remembering to rotate the tapes (my life tends to be extremely busy). The result: no backup. I decided I needed a solution that wouldn’t require me to change tapes.

In addition, being a freelance writer, I don’t follow a nine-to-five schedule. If I write at 4:00 A.M. and my data isn’t backed up until midnight, that leaves 20 hours per day in which something could happen to my server, potentially causing me to lose that day’s work.

In my situation, DVD-RAM proved to be the perfect solution. The Windows 2000 backup program is capable of backing up data to a file on a hard disk. It isn’t just limited to backing up data to tape. My backup solution was to install two DVD-RAM drives into my new server. Each night at midnight, Windows 2000 backs my data up to a file on both DVD-RAM drives.

Why two drives? This allows me redundancy because I have two copies of the backup file. Once a week, I have my backup program erase the existing backup file and create a new one. Each day for a week, all subsequent backups are appended to the first one, until it’s time to wipe the drive and start over.

Even DVDs eventually fill up, though. With two drives, I can clear the old backup file on different days. One drive is set to clear the backup file on Monday, while the other drive is set to clear the backup file on Thursday. I’ve always got a few days worth of backups on hand no matter what day of the week it is.

As for the problem of losing an entire day’s writing should the server go down before midnight, DVD-RAM solved that one too. Unlike a tape drive, you can write files directly to a DVD-RAM drive without having to use special backup software. I decided to take advantage of this feature by creating a batch file to copy all of my data to a special directory on the DVD. I made the batch file accessible through an icon on my desktop so that after I write something, all I have to do is double-click on the icon to create a temporary backup. My batch file is designed to overwrite the previous temporary backup to conserve space on the DVD.

The problems begin
Unexpectedly, the DVD-RAM drives I received with my new server didn’t look and function like CD-RW drives. I had a tough time getting my new server up and running because I had assumed the new DVD-RAM would function like the types of drives I was familiar with. During the course of setting up the system, I made several blunders. At the risk of embarrassing myself, I’ll tell you about some of the issues I faced so that you don’t make the same mistakes. (Like many experienced computer users, I must admit I didn’t read the directions first!) Keep in mind that other brands of drives may work differently than my Creative Labs DVD-RAM. Make sure you follow the directions that came with your drive.

As with any new server, my first step was to load an operating system (in this case, Windows 2000). Because a DVD-RAM drive read CDs as well as DVDs, I had originally ordered my new server without a CD-ROM drive. This, however, proved to be a mistake. At the time that I ordered the server, I knew that the DVD-RAM drives were SCSI-based, and therefore wouldn’t work with the standard driver used for IDE CD-ROM drives. I didn’t think this would cause a problem because I ordered the server with an Adaptec SCSI controller for which Windows 2000 had drivers.

You’ll need a CD-ROM, too
The Windows 2000 Setup program, as I predicted, detected my Adaptec SCSI card. Unfortunately, though, Setup wouldn’t detect my DVD-RAM hardware. I had assumed that Windows 2000, being relatively new, would contain DVD-RAM drivers, or that it would recognize the DVD-RAM drive as a SCSI CD-ROM drive, but I had no such luck. I ended up having to install a CD-ROM drive before I could even load Windows onto the server. To make a long story short, make sure that any system with a DVD-RAM drive also has a normal CD-ROM drive.

Don’t forget drivers
My next problem was that Windows 2000 only recognized the DVD-RAM drives as generic mass storage devices. Therefore, I decided to install the drivers that came with the devices. Unfortunately, the driver was for Windows 98 only. Searching the Web, I discovered that the only available driver was included with a product called WriteDVD! Although WriteDVD! is a very nice product, it costs $89.95. So much for downloading a free driver.

How does this thing work?
After receiving a copy of WriteDVD!, installation was a piece of cake (look for a review of WriteDVD! in a future Daily Feature). The problems came into play when I tried to access my DVD-RAM drives. As you can see in Figure A, the drive’s media tray is recessed and contains a spot to place a CD or a DVD. As you can see in Figure B, however, a DVD-RAM disk is contained in a cartridge, much like the old CD-ROM caddies. The main difference is that the DVD-RAM media can’t be removed from the cartridge.

Figure A
Each DVD-RAM drive contains a media tray.


Figure B
The DVD-RAM media resembles an old CD-ROM caddy.


Because of the difference in the shapes of the media tray and the DVD-RAM media, I assumed that you could just pop out the media tray and insert the DVD-RAM cartridge. Once again, I was mistaken. The DVD-RAM cartridge actually sits on top of the media tray. I spent almost a week trying to figure out why my drives wouldn’t recognize DVD-RAM media before I accidentally inserted a cartridge on top of the media tray and it worked.

Preparing a DVD-RAM cartridge
A DVD-RAM cartridge is very different from the DVDs used for movies. The difference isn’t just the plastic enclosure around the media, however. As Figure C shows, the DVD-RAM media is etched with hundreds of small rectangles. Also notice in the figure that the DVD-RAM cartridge indicates that the media has a 5.2-GB capacity and is double-sided. Don’t let that fool you. 5.2 GB is the total capacity of the cartridge, not the capacity of each side. Unfortunately, most DVD-RAM drives (including mine) are single-sided. This means that to utilize the entire capacity of the media, you have to flip it to access the B side.

Figure C
The DVD-RAM media is etched with hundreds of small rectangles.


The total capacity of the media is also limited by the file system. As with most other types of media, you must format a DVD-RAM disk before you can use it (some brands come preformatted). To format DVD-RAM, you can use a program called Format UDF! that comes with WriteDVD! As you can see in Figure D, Format UDF! gives you a choice of file systems to use.

Figure D
You can format the DVD-RAM media with a variety of file systems.


Formatting DVD-RAM drives
As with hard disks, DVD-RAM drives can be divided into multiple partitions. If you choose to use the FAT16, FAT32, or NTFS file systems, your total number of partitions is limited only by the number of free drive letters (and by the fact that the minimum size for a FAT32 partition is 512 MB).

In the version of WriteDVD! that I’m using, UDF versions 1.02, 1.50, 2.00, and 2.01 are supported. UDF file systems support only a single partition per drive and are used as the default file system for DVD-RAM under WriteDVD!.

If you’ve never heard of the UDF file system, you’re not alone. UDF (Universal Disk Format) has been around for a while, but it isn’t highly publicized. UDF can be used by most newer Windows operating systems, and it gets around all of the cluster size problems found in other file systems, such as FAT16’s 2-GB limit or those insanely large 64-KB clusters that are found on some large hard drives. UDF uses 2-KB cluster sizes.

UDF offers full support for Unicode’s special characters, which makes it ideal for a cross platform file system, or for use in situations in which multiple languages are being used. Unicode supports long file names up to 255 ASCII characters or 127 Unicode characters.

One final benefit of UDF that deserves to be mentioned is that it’s optimized for large files. No matter how large a file is, it can be managed in one single extent. Therefore, UDF doesn’t require as much overhead as some other types of file systems. UDF works fine for small files too.

Conclusion
In this Daily Drill Down, I’ve explained why DVD-RAM is the logical storage solution on some networks. I also discussed some backup and storage techniques that seem to work well with DVD-RAM drives, and the hardware and software requirements for DVD-RAM use in Windows 2000.
The authors and editors have taken care in preparation of the content contained herein but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.

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