AIX Tip of the Week

AIX Tip of the Week: Split Mirror Copy Saves Backup Time

Audience: IT Managers and Administrators

Date: April 3, 2000

AIX in the News: According to a report just released by industry consultant D.H. Brown, AIX ranks #1. For details, see

And now for the tip: The "split mirror copy" technique can be used to reduce downtime for backups to seconds. The technique splits off a copy of a mirrored file system and mounts it as read-only for use as an online backup. The AIX 4.3 command to do a split mirror is trivial:

chfs -a splitcopy=/backup -a copy=2 /testfs

It takes about 15secs for 2GB on my machine. The pro/con's of split mirror backups are discussed in the attached PDF file.