Hong Kong hotel rooms at 2:00 a.m. local time as they are during business hours. A good enterprise network never goes
down.
As you can see, backup is different today, and it needs different software. Heterogeneous networks are the norm, and intranets are taking over the LAN world. With a large LAN , you may very likely have several different servers providing backup services with just as many backup media devices. Thus, you need backup software that can not only speak different computer dialects but also cope with different tape formats. Last, but far from least, the software must be able to catalog and track them all in a centralized database. If you have a NetWare-based LAN , you need
client agents
-- small programs that enable "foreign" systems (running anything from the Mac OS to Unix to Windows 95) to hook up with the backup program.
BYTE has tested a couple of products that satisfy these massive requirements: Cheyenne Software's ArcServe 6.0 and Stac Electronics' Replica 2.1. Both programs are primarily NetWare oriented; however, each is also available in an NT-server version.
The
se two programs take vastly different approaches to network backup. ArcServe, honed by years of experience, employs a standard file-by-file backup and recovery system, while relative newcomer Replica mirrors entire NetWare volumes. Besides this major difference, there are a number of other small dissimilarities between the programs. Each approach has its advantages for particular situations.
Although ArcServe has been around in some form for nearly as long as NetWare, version 6.0 isn't your father's ArcServe. This new version comes with a host of new features, the most important being what Cheyenne calls Push Agents.
Unlike agents that supply you with data from non-Novell sources, ArcServe's Push Agents manage multiple
system-file access
. These agents allow multiple data streams, so ArcServe can back up data from multiple servers across the network simultaneously. This, in turn, produces faster throughput. In short, ArcServe works as an honest-to-goodness multitasking, multiproce
ssing backup system; it's not like the old-fashioned, one-job-at-a-time, batch routine that we all know and hate.
You may wonder whether the existence of multiple Push Agents makes much of a difference when they're all writing to the same storage device. Indeed it does, because ArcServe uses another technique, called
media pooling
, to maximize backup speeds by writing to multiple backup devices at once. The result is the fastest file-to-tape backups we've ever seen.
ArcServe has even more tricks up its sleeve. It can use multiple backup devices as RAID Level 5 devices, so even if you lose one tape out of a backup set, you won't lose any data. RAID 5 takes up more tape space, but it ensures that not one byte of data is lost without ArcServe's noticing it and making the appropriate on-the-fly repairs. The RAID 5 implementation, a technology that is mainly used with secure servers, raises this program far above the common herd of file-by-file backup programs. If you want utmost reliability, then
choose this option.
Replica, on the other hand, roars by ArcServe when it comes to backing up and restoring an entire NetWare volume or directory tree. By mirroring only the data in active file systems, and not simply
replicating a disk image
sector by sector, Replica leaves older image-backup technology eating its dust. System administrators get a faster system-mirroring solution that needs far fewer tapes.
How fast is Replica? On our 120-MHz Pentium Windows NT server with a Travan TR-4 tape drive, we saw 5 GB per hour go whipping by like mile markers on the highway at 80 mph. And that was with a Travan drive, which doesn't come close to the raw throughput of a digital audiotape (DAT) or 8-mm tape drive.
Interestingly, although Replica works best at the volume/directory-tree level, it can also copy non-volume-specific information, such as an MS-DOS partition, without a hitch. At a time when you need a scorecard to keep track of which machines are using which file systems, i
t's a true pleasure to have a backup system that doesn't care whether the file system being used is file allocation table (FAT), High Performance File System (HPFS), NT File System (NTFS), or whatever. Replica instantly recognizes the format.
Stac's Object Replication Technology (ORT) also adds flexibility, enabling you to store entire file systems on other servers, tape drives, or even completely different types of storage devices, such as magneto-optical (MO) drives. Better still, Replica can recognize most available storage options, and it automatically presents them to you as possibilities; you don't have to fiddle with configuration files to ensure the program knows about the MO drive here or the 8-mm library over there.
Restoring files is almost fun with Replica. With NetWare, for instance, you use the program to see the backup media as a volume, assign it a drive letter, and use the usual file-copy and move commands.
When you combine this feature with Replica's imaging capacity, you can eve
n perform such miracles as restoring a dead NetWare server with just two disaster-recovery floppies and a copy of your backup media. This is distinctly reminiscent of Unix, where you can run the OS straight off the tape if you're desperate.
Which One Is Best?
These programs are intended for two different audiences. If you want to clearly see the granularity of file systems -- such as when you're in desperate need of one particular file -- then ArcServe is for you. Its file-searching and restore speeds are great. And its RAID 5 option makes it potentially the safest backup system currently on the planet. Still, you pay a hefty price, both in total backup time and in the $1995 cost of the software.
If you're more likely to want to back up and restore entire systems, even from the brink of server failure, then Replica is what you want. Its major weakness is that, whether you're backing up or restoring, the program will bring other network activity to its knees. Moreover, the program
is simply not in the same ballpark as ArcServe for finding and restoring individual files. Still, with its $995 price, you may be able to forgive these sins.
Thus, picking between these two products is both simple and complex; there is no clear editor's choice here. Both are great, but they do somewhat different jobs. You need to analyze your network use carefully to see what your users and your network need most. Only then can you make a reasonable choice between these very different products. But no matter which one you choose, you're going to have a first-rate backup system that should see you through to the end of the century.
Where to Find
ArcServe 6.0.................$1995
Cheyenne Software
Roslyn Heights, NY
Phone: (800) 243-9462
Internet:
http://www.cheyenne.com
Circle 1047 on Inquiry Card.
Net Saviors
