Using Remote Storage To Extend Available Storage Space
In the early 1990’s, I started my first job as a network administrator. At the time, I was working for a large insurance company with an enterprise class network. The company’s largest file server had about a gigabyte of storage space. I remember thinking that it would take an eternity for the users on that server to consume a gigabyte of disk space. Today though, there are consumer grade PCs that come standard with a half a terabyte of storage space. It boggles my mind to think about how much disk space a large enterprise requires.
For many large organizations, there comes a point when the existing systems simply won’t support adding any more storage without investing in additional hardware (new servers, SAN, NAS, etc.). If the organization is budget strapped, one solution to containing the ever growing collection of user data is to implement remote storage. In this article, I will show you how.
What is Remote Storage?
To understand what remote storage is and how it works, imagine that you have a server with a terabyte of disk space. That sounds like a lot, but if you have a thousand users, then your server has a total capacity of less than one gigabyte per user. That’s still quite a bit of space, but depending on what type of files the users are creating, a gigabyte can be used up quickly. At any rate, let’s assume that you are burning through your disk space at an uncomfortable rate and setting disk quotas is not an option.
One thing that you can do to cope with the problem is to implement remote storage. The idea behind remote storage is that it allows you to use space on backup tapes as disk space. To put it bluntly, it allows you to lie to your server about how much free disk space it has.
Those of us who work solely with PCs have traditionally been conditioned to think of tape drives only as a backup mechanism. However, Windows Server’s remote storage feature allows you to use a tape in the same way that you would use a hard disk. Let’s say for example that your terabyte of disk space was just about filled to the limit. Obviously, Windows does not want you to run out of disk space. To prevent this from happening, Windows goes through your user’s files looking for files that have not been used in a long time. When such files are found, they are moved from the hard disk onto tape.
OK, let’s stop right there. Moving old files from disk to tape probably sounds more like archiving than increasing the machine’s overall storage capacity. There is a difference though. With traditional archiving, the tape is locked away in a vault, usually never to be seen again. With remote storage, the tape stays online. If a user looks at the contents of their home directory, they will continue to see all of their files, regardless of how long it has been since a file has been used. If a user decides to use a file that has been moved to tape, the system simply retrieves the file from tape and moves the file to the hard disk.
Isn’t Remote Storage Slow?
Every time that I have tried to explain remote storage to someone in the past, it is inevitable that when I get to this point, they ask the question “sure it works, but isn’t it slow?” Well, slow is a relative term. Tape drives are a whole lot faster than they used to be. The HP StorageWorks Ultrium 960 tape drive for example boasts a 160 MB/s sustained transfer rate. Of course it still takes time to locate the necessary file on the tape and to copy the file to the server’s hard disk, so yes, the process takes a little bit longer than if the file were read directly from the server’s hard disk.
Although it does take more time for the server to access a file from remote storage than it does to access a file from the server’s hard disk, things are really not as bad as they sound. Remember that only files that have not been used for months are moved to remote storage. Odds are that most of the files that get moved to remote storage will probably never be used again. For example, on my own network, I have financial records dating back to 1994. There’s no way that I am ever going to need these records again (I hope), but my accountant insists that I keep them for legal reasons. The same thing goes on in corporate networks. Employees are being pressured to keep all documents for legal reasons, even if the document is no longer useful.
My point is that you might occasionally have a user access a file that’s in remote storage, but it’s not something that is probably going to occur on a daily basis. Sure, users will notice that it takes a little longer to access really old files, but they probably won’t be accessing these files often enough for it to make a difference to anyone. Otherwise, the files wouldn’t have been moved to remote storage in the first place.
How Much Space Can You Gain?
Now that I have talked about what remote storage is and how it works, you might be wondering how much storage space you can really gain by using remote storage. I’m by no means a tape drive hardware expert, but I did a quick check on the Internet to see how much data could be stored on a high capacity tape. I’m not sure if this is the highest capacity tape available or not, but the LTO 3 tape media can hold 800 GB of data (compressed).
If we go back to my previous example of a file server with a terabyte of storage that is quickly filling up, you can see that adding 800 GB of storage space in the form of remote storage would almost double the server’s total capacity. Of course there are plenty of servers out there with much more than a terabyte of disk capacity. For higher end servers, you could always use an auto loader with a 16 tape magazine. Sixteen tapes at 800 GB each would provide you with twelve and a half terabytes of remote storage space.
Setting up Remote Storage
To setup remote storage, open the Control Panel and double click on the Add / Remove Programs icon. When you see the Add / Remove Programs properties sheet, click the Add / Remove Windows Components button. Next, select the Remote Storage check box from the resulting window and click the Next button to continue. Windows will now copy a few files and ask you to reboot the server.
When the computer reboots, go to the Start menu and select All Programs | Administrative Tools | Remote Storage. When you do, the Remote Storage Setup Wizard will launch. The wizard will ask you which volume you want to manage, and will detect your removable media. The wizard will also help you set a schedule for moving old files to remote storage.
Reconfiguring Remote Storage
It’s likely that as time goes on, your remote storage needs will change. You may want to add or remove volumes from the remote storage list for example. Fortunately, remote storage is very flexible. If you want to add a volume to the remote storage list, simply slect the Remote Storage command from the Administrative Tools menu. Since the Remote Storage Wizard has been run once already, selecting this menu option will take you directly to the Remote Storage console rather than launching the Remote Storage Wizard.
When the management console opens, right click on the Managed Volumes container and select the New | Managed Volumes command from the resulting shortcut menus. Doing so will launch the Add Volumes Management Wizard. The Add Volumes Management Wizard works very similarly to the initial remote storage setup. Just use the wizard to select which volumes you want to manage.
The Managed Volumes container can also be used for changing the stipulations for moving a file to remote storage. To do so, right click on a volume and select the Properties command from the shortcut menu. When the volume’s properties sheet appears, select the Settings tab. The Settings tab allows you to control the desired amount of free disk space on the volume, the minimum size of files that are to be moved to remote storage, and the amount of time since the file has been accessed.
In this article, I have explained that remote storage provides you with a way of increasing your server’s total storage capacity by moving old files into a continuously accessible archive. It’s important to keep in mind though that there are many different ways of increasing a server’s available storage space. Implementing remote storage may not always be the most cost effective method or might not be right for your organization’s individual needs. I therefore recommend considering the cost and the impact of other types of storage prior to investing in remote storage.