When looking at a potential backup product, there are many questions that you should ask yourself:
Does the product fully support my platforms?
Does the product back up raw partitions?
Does the product back up very large filesystems and large files?
How will the product help me meet extremely aggressive requirements?
Does the product back up many clients to one drive simultaneously?
Can the product automatically create multiple simultaneous backups from one client?
Does the product handle data requiring special treatment?
Does the product have storage management features?
Does the product reduce network traffic?
Does the product support a standard or unique backup format?
How easy is the product to administer?
How secure is the product?
How easily does the product perform recoveries?
How well does the product protect the backup catalog (e.g., database, index)?
How robust is the product?
How automated is the product?
Can the product verify its volumes?
What does the product cost?
What vendor is selling the product?
Full Support of Your Platforms
One of the easiest ways to narrow the list of backup software vendors from which to choose is to find out who supports the platforms you are running. There is no reason that a vendor should have to answer an RFI with hundreds of questions if it doesn’t support most of your platforms. By the same token, there is no reason you should have to read the answers to hundreds of responses from more than 50 vendors. Before getting into the nitty-gritty features, simply find out who supports all or most of the platforms that need to be backed up.
The key word in the previous paragraph is “most.” Most shops are becoming increasingly heterogeneous, with a number of Unix variants, Intel-based operating systems, and any number of database-like products. In such a shop, there are always a few boxes that run a “different” version of Unix, an older version of Windows, some other operating system, or even a lesser-known database product that most products don’t support. During the first cut, include products that back up most of the operating systems that you are running. Restricting the search to only those that handle every platform might exclude some very good products or force the selection of the wrong product. Many vendors will consider porting their products to a new operating system or database if a potential customer asks them to do so, although this may come at a cost. (In the final analysis, however, a product that has been supporting a particular platform for a while usually supports it better.)
There are many different operating systems out there. There are Unix variants, Mac OS, various Windows flavors, NetWare, and mainframe operating systems. Most of the big products handle almost all of these. There was a time when you had to purchase one product for the Novell servers, one for Windows, one for Mac OS, one for the MVS mainframes, and yet another for the Unix servers. Today, some products handle all of those from one console. However, the rush by so many large backup products to support everything has left a few holes. There are a number of examples of this. Things that are typically left out in Unix are block special files, character special files, and named pipes. Microsoft’s System State and Active Directory also are occasionally left out, Mac OS resource forks are forgotten, and Novell’s NDS is left out as well. Make sure each product fully supports the platforms it claims to support.
Should You Back Up Special Files?
If a backup product did not back up the Windows Registry, it would not be considered certified by Microsoft. However, some prominent Unix backup packages don’t back up special files and named pipes. (These are special types of files in Unix and Linux.) If the operating system is lost, their typical answer is to “reinstall the operating system and our software, and then start the restore.” This takes too much time and involves writing a lot of information twice. If the backup system backed up the special files, there is a much quicker way to recover from the loss of the operating system.
What if a system was able to boot, but the /dev directory was all messed up? Being able to restore those files can reduce the number of hours of downtime. Does the backup product really need to back up the device files? Yes it does!
Many environments use their commercial backup product to back up raw partitions. A partition is a section of disk that may or may not contain a filesystem. Typically (although not always), when you refer to a raw partition, you are referring to a section of disk that does not contain a filesystem. This disk may contain data for a database product, such as Oracle, Informix, or Sybase. It also may be the first part of the root partition of the operating system disk that contains the boot block. Since most backup products are designed to back up files that reside on a filesystem, they may not be able to back up a raw partition.
The ability to back up raw partitions could help when backing up relatively small databases that reside on raw partitions. To back up most databases with a product that supports raw partitions, simply shut down the database and tell the backup software what raw partitions to back up. In order to do this, the backup software needs to be able to back up these raw partitions.
The second reason to consider the use of this feature is to back up the root partition of an operating system disk. It’s another way to recover the root disk without reinstalling the operating system. There are two essential parts to the operating system disk. The first is the operating system itself, which resides on one or more filesystems on that disk. The second is the boot block (in Unix variants) or Master Boot Record (in Intel systems). This tells the system’s firmware where to go to find the operating system kernel. This block of data normally can reside on the first slice, or root partition, of the operating system disk. In modern Linux systems, it resides in a special partition called /boot. It resides outside the “normal” filesystem and thus is not backed up by normal procedures. If the backup product is able to back up the raw partition on which it resides, it’s possible to recover it without reinstalling the operating system.
Many of the popular backup packages now work with raw partitions. There is one drawback to backing up raw partitions, though. A raw partition is seen as one big file. That means that every time it is backed up, the entire partition is backed up. With a 100 MB root partition of an operating system, this is not a problem. If it’s a multiterabyte raw device, it can fill up quite a lot of backup media very fast. Some products can intelligently read a raw partition and perform an incremental backup of its contents.
