All approved UDF 2.60 DCNs
All approved UDF 2.60 DCNs
All approved UDF 2.60 DCNs
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<strong>All</strong> <strong>approved</strong> <strong>UDF</strong> <strong>2.60</strong> <strong>DCNs</strong><br />
6.x.1 Characteristics of Media formatted for Pseudo OverWrite<br />
Media formatted for Pseudo OverWrite will support multi-track recording. <strong>All</strong> logical<br />
sectors in the volume space on the media can be overwritten.<br />
The file system can write concurrently to multiple tracks. A track is defined as reserved<br />
or used, see 1.3.2. Each track is sequentially recordable only. The Next Writable Address<br />
(or NWA) is obtained by the file system by querying the drive and points to the next<br />
recordable logical sector within the track.<br />
In addition to sequential recording, any logical sector in a track before the NWA can be<br />
independently overwritten. Also sectors in a used track (having no valid NWA) can be<br />
overwritten. Overwriting is supported by the drive by recording updated data either<br />
within the Spare Area (by the linear replacement algorithm) or to some NWA within the<br />
volume space. <strong>UDF</strong> does not currently propose any policy specifiable by the file system<br />
to control physical placement of data being overwritten.<br />
While performing sequential recording on the medium after requesting the NWA of a<br />
track, the drive system shall behave in such a way that the NWA will not change<br />
unexpectedly, or without notification, until the <strong>UDF</strong> implementation queries for the<br />
NWA of that track again. When pseudo overwrite is performed all the NWAs become<br />
invalid.<br />
The drive is entirely responsible for maintaining the remap entry information for the<br />
logical sectors that can and may be persisted within the volume space.<br />
6.x.2 Write Strategy<br />
Tracks can be utilized to record different data types in a logically contiguous manner (e.g.<br />
metadata, metadata mirror and data, can be recorded in separate tracks). When all<br />
unrecorded sectors in a reserved track have been exhausted, the <strong>UDF</strong> implementation can<br />
assign a new reserved track (by splitting any existing reserved track) of an appropriate<br />
size.<br />
By allowing reserved tracks to be split, the drive enables recording of the AVDP<br />
(comprising volume structure) at any two locations of: LSN 256, the last LSN in the<br />
volume, or (Last LSN – 256) as per ECMA 167.<br />
It is desirable for <strong>UDF</strong> implementations to duplicate the metadata in the Metadata Mirror<br />
File.<br />
<strong>All</strong> <strong>approved</strong> <strong>UDF</strong> <strong>2.60</strong> <strong>DCNs</strong> 32 February 28, 2005
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