With
iXOS-JUKEMAN, writable disks like CD-Rs, WORMs, and rewritable disks can be
written incrementally. If a disk is initialized using the IFS, it appears as a
writable file system. Before actually writing to disks, the server stores data
in a buffer temporarily. It is the administrator's task to initiate writing the
buffer contents to the disk. The difference between data in the buffer and
data, which is already on disk, is not visible to the user. The administrator
can finalize the disk, which will then be converted to the ISO 9660 file system
format. Afterwards it is read-only, but does not use up the resources of the
IFS buffer.
Note that you require a valid license key if the writer is to burn more than
128 MB to a disk.
To enable incremental writing, iXOS-JUKEMAN needs a global file system buffer
on the hard disk. As soon as the buffer is configured, files can be copied to
the disks. The buffer is configured by setting its size and the maximum number
of files ("inodes"), that can be stored in the buffer.
To determine the correct buffer size and number of inodes, keep in mind that
each file or directory on an unfinished disk requires an inode and that the
size should be sufficient to buffer all data you plan to transfer via the
buffer.
Any changes to the IFS buffer configuration (i. e. name, size, number of
inodes) will cause the buffer contents to get lost. Therefore, you should
"flush" the buffer contents to all disks that are not already finalized (see
section "Burning disks incrementally" on page 154) before changing the
configuration. The server will automatically read the directory structure of
IFS disks, when a new buffer is created.
As an alternative to a single IFS buffer iXOS-JUKEMAN 2.3 supports several
independent IFS buffers. See "IFS with several independent buffers" on page
251.
*
IFS-CDs cannot be copied byte by byte with cdglow, even if they are
finalized. However, it is possible to copy them logically, thus creating a CD
with the same contents, but at least with a different time stamp.
* The IFS is case sensitive. Therefore it should only be accessed through views
with the same file name filter (see "Volume name space and file name filter" on
page 69).
* CDs that are not finalized should not be deleted from the volumes
database, as this will cause loss of buffered data.
IFS
2.3 cannot read IFS buffers of previous versions. All buffered data that has
not been "flush"ed will be lost. Non-finalized CDs of version 2.2 can be
read.
IFS 2.3 also detects non-finalized CDs from version 2.1 with some restrictions.
The parameter oldifs must be set to 1. Then IFS 2.3 will read
non-finalized CDs from version 2.1 in read-only mode. These CDs can be
finalized with the same restrictions as given below for incomplete tracks.
The
IFS writes CDs in individual tracks. If an error like a power failure, a
"buffer underrun" or a hardware failure occurs during the writing process, the
CD will carry an incomplete track.
It might then be necessary to deactivate the jukebox, switch it off, and
re-activate it, before the drive will be able to read CDs again. Afterwards,
iXOS-JUKEMAN must test the CD again.
The IFS tries to read the last track, and detects it as incomplete. It does not
analyze this track and does not delete the buffered data it tried to write to
the track. The CD is presented to the user as before.
However, there are some important differences. The IFS presents the CD as write
protected. No data can be modified through the file system. The IFS permits no
further "flush" for these CDs. "purge" is possible and deletes the buffered
data. Finalize is possible with clear restrictions.
Some drives cannot write to or finalize CDs with a corrupt track at all. If the
drive can finalize a CD, the result is to be used with restrictions only. The
data buffered for this CD is deleted. The ISO 9660 header is incomplete, the
path table is missing. NT cannot read the data any more. iXOS-JUKEMAN can read
it since the path table is ignored here. The recorder that finalized the CD
will be able to read it, but other drives may not.
The GUI offers a "finalize" button only if no data are buffered. The user
achieves this by clicking "purge". The buffered data will then be lost.
It is advisable in most cases to copy the data of a CD with a bad track as soon
as possible. Afterwards the old CD should be finalized, so that the IFS deletes
it from the buffer completely, and the CD should not be used any more.