output device, such as a tape drive, is slow then the encryption process will get slowed down and you may not notice the extra load. If you are writing to a high-speed device, such as a dump area on a disk, then the CPU load from the encryption process could be very high. It is always best to run some load tests beforehand. If server performance is an issue, you can look at interface devices which can perform encryption. A number of PCI-bus SCSI controllers can perform this, and there are also some hardware devices, such as the CryptoAccelerator PCI Card which can offload the encryption work into a hardware device. There are also some devices which can connect between a host and a storage device which perform encryption, such as NeoScale's CryptoStor Tape devices. And of course, there are a number of tape drives which can perform encryption from vendors such as IBM and Sun. But be careful when using hardware appliances, and always plan for what steps you will need to take if that encrypting device stops working - make sure you can extract and reuse the encryption keys. Also be aware then encrypting data will affect how well it can be compressed - whether you are using software or hardware compression. The ideal encryption algorithm will generate an output stream which is perfectly random, and cannot be compressed. So, if you want compression with encryption, it would be best to perform compression first and then apply encryption