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Linux Magazine: VXA-1: Swift, Silent Backups

Jul 29, 2000, 17:04 (2 Talkback[s])
(Other stories by Lou Grinzo)

[ Thanks to Robert McMillan for this link. ]

"The best protection against hardware failures and user errors is to back your system up on a regular basis. Ecrix's attempt to make backup chores less taxing is the VXA-1 tape drive, which stores up to 66 GB of compressed data per tape cartridge."

"Another key issue Ecrix is addressing with the VXA-1 is the reliability of backups. We've all heard stories of the sysadmin who, under pressure, discovers that a tape drive can't read a backup it created and verified just days ago. Unlike other tape drives, the VXA-1 mimics the way TCP/IP data is sent across the Internet. TCP/IP breaks your data into packets and then reassembles it at the destination, even if the packets have arrived in a different order from that in which they were sent. Similarly, the VXA-1 stores your data on tape in 64-byte pieces, each tagged with error-correction information and an identifier that indicates its place in the data stream. This allows the drive's four heads to try to read each data packet independently -- possibly reading them out of order when the tape is misaligned, damaged, or stretched -- and still rearrange them as needed."

"The external VXA-1 we tested worked extremely well. We attached it to an Adaptec 2940AU PCI card and accessed it from Linux as /dev/st0. We performed backups of an entire Linux installation using Merlin Software Technologies' PerfectBackup, and also wrote a single file of several hundred megabytes to the drive with the tar command. We also tested the drive briefly with the BRU and Arkeia backup programs."

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