Backing up your data is a job thats simple when done badly: doing it properly requires ongoing effort. Its easy to get complacent about your backup routines, particularly when the network is small and consequently suffers from few failures. Its an accepted fact that a large percentage of smaller businesses never fully recover from the financial consequences of the loss of critical data.
If youve set up your system so that all critical data and documents are held on one or two servers, your job is easy. The best way to keep your servers up and running continuously and protect your data at the same time is to use RAID (redundant array of inexpensive disks). There are two types of RAID that provide fault tolerance: the simplest is RAID-1 (mirroring). For RAID-1 you need two hard drives, preferably of the same capacity. The two mirrored drives appear as a normal single volume, the same size as the smaller of the physical volumes. Data is copied to both drives, so in the event of one failing, the other carries on seamlessly.
RAID-5 (disk striping with parity) doesnt waste much disk space, but needs a at least three drives. The data and parity reconstruction information are striped across the disks, so if one fails, the missing data can be reconstructed from the parity information on the others. Windows 2000 Server and NT 4 Server have RAID-1 and RAID-5 facilities built in. The disadvantage of RAID is you take a performance hit when writing data, and also when reading if a RAID-5 disk fails while the system is dynamically reconstructing the missing data. There are various hardware RAID solutions available, and for the lower-end servers with EIDE drives likely to be used in our small network, Promises FastTrak66 card (www.promise.com) is a good option.
RAID wont protect you from fires or burglary, or protect locally-held data. Consequently, all networks need a tape backup drive, automated backup software and a sensible and cautious backup routine. Go for a well-established, professional package such as Veritas Backup Exec (www.veritas. com). It isnt cheap, but its comprehensive, reliable and expandable. A big pitfall you need to be aware of is that most backup software isnt able to backup open files by default, so if for instance your client machines Outlook PST files are local and its left running overnight, the data wont be protected. Backup Exec provides an add-on option for open file backup, which you should consider.
There are numerous different backup methodologies, but at the very least you should maintain six tapes. You should take a full system backup on two tapes every Friday, and take one of them off-site. The remainder of the week you should perform incremental backup on the other four.
This is only a minimum though, and the more valuable your data the more frequent and comprehensive your backups should be. Monitor your backup log files regularly to make sure everything is going as it should. Finally, never leave it to the moment disaster strikes to actually try and restore a backup.
This Feature appeared in the September, 2000 issue of PC & Tech Authority Magazine