1-30 IBM Informix OnLine Database Server Administrator’s Guide
Logical Log Tape Device Guidelines
OnLine supports a logical log backup option called Continuous-Logging,
which backs up each logical log as soon as it becomes full. The Continuous-
Loggingoption is recommended for all OnLine configurations, but it requires
a dedicated tape device while the option is active.
Informix strongly recommends that your OnLine environment include two
tape devices, one for continuous backup of the logical logs and one for
archiving.
LTAPEDEV
LTAPEDEV specifies the logical log backup tape device.LTAPEDEV can be a
link pathname that points to the actual tape device to provide flexibility in
case the actual device is unavailable.
The default value of LTAPEDEV is/dev/tapedev.
You can set the value ofLTAPEDEV to /dev/null if you are testing an appli-
cation or if you are using OnLine in a learning environment. The only
advantage of doing this is to eliminate the need for a tape device. However,
you cannot recover OnLine data beyond that which is stored as part of an
archive.
You can set the value ofLTAPEDEV to specify a tape device on another host
machine and perform logical log backups across your network. For instruc-
tions on how to do this, refer topage 3-19.
Tapedevices that do not rewind automatically before opening and on closing
are considered incompatible with OnLine operation.
LTAPEBLK
LTAPEBLK specifies the block size of the logical log backup tape device, in
kilobytes.Specify the largest block size permitted by your tape device. If the
pathname of the tape device is /dev/null, the block size is ignored. The
default value of LTAPEBLK is 16KB.