Version 5.01 beta 1
1. RAR 5.0 archives can include an optional quick open information
controlled with -qo[-|+] switch. It allows to open the archive
contents in graphical interface faster.
This version provides better update peformance for archives
containing both quick open information and service records,
such as NTFS file security. Also default parameters of quick open
information are optimized to achieve faster open time for such archives.
2. Bugs fixed:
a) "Test" command could erroneously report damaged data in valid
recovery record if only a part of files in RAR 5.0 archive
was tested. It did not ...view middle of the document...
0 format includes Intel IA-32 executable and delta
compression algorithms, but RAR 4.x text, audio, true color
and Itanium algorithms are not supported. These excluded algorithms
are not efficient for modern data types and hardware configurations;
e) RAR 5.0 decompression can utilize several CPU cores.
Though not to same extent as in compression algorithm,
it improves the decompression speed on large files
with poorly compressible data or when using BLAKE2 checksums.
3. Changes in RAR 5.0 archive format:
a) file times are stored as Coordinated Universal Time (UTC)
instead of former local time, making file exchange among
several time zones more straightforward;
b) file names and archive comments use UTF-8 encoding.
4. RAR 5.0 recovery record is based on Reed-Solomon error correction
codes. If recovery record size is large enough, 5% and more,
the new error correction scheme provides much higher resistance to
multiple damages comparing to RAR 4.x recovery record.
Smaller record, such as 1 - 2%, or less random damage type would
result in less difference between 4.x and 5.0. For single continuous
damage 4.x and 5.0 efficiency is about the same.
Additionally to usual data erasures, the new recovery record
is able to detect deletions and insertions of much larger size
than in previous RAR versions. Maximum insertion size is several
megabytes. Maximum deletion size depends on the damage type
and in some cases can be as large as the recovery record size.
Still, the best recovery performance and efficiency is achieved
if no deletions and insertions are present, so all data including
damaged sectors preserve their original positions. Thus, if you use
some special software to copy an archive from damaged media,
it is better to choose the mode, when damaged sectors are filled by
zeroes or any other data instead of cutting them out completely
from resulting file.
RAR 5.0 recovery record is more resistant to damage of recovery record
itself and can utilize a partially corrupt recovery record data.
Note, though, that "Repair" command does not fix broken blocks
in recovery record. Only file data are corrected. After successful
archive repair, you may need to create a new recovery record
for saved files.
New recovery record is not based on 512 byte sectors anymore
and incorporates more complicated data structures. So it is impossible
to specify its size in sectors. For RAR 5.0 archives the parameter of
-rr[N] switch and rr[N] command is always treated as a percent of
archive size regardless of presence of % character. Typically N%
recovery record can repair up to N% of continuously damaged data
and increases the...