Archive name and parameters dialog: options
All delete options listed below modify the behavior of "Delete files after archiving" from General options. They have an effect only if "Delete files after archiving" is on. You can enable any of these options in the default compression profile to change the default behavior of "Delete files after archiving".
Delete files normally. Files are deleted permanently, but not securely, so sometimes it may be possible to recover them using special software.
Deleted files are placed to Recycle Bin.
Before deleting file data are overwritten by zero bytes to prevent recovery of deleted files, file is truncated and renamed to temporary name.
Please be aware that such approach is designed for usual hard disks, but may fail to overwrite the original file data on solid state disks, as result of SSD wear leveling technology and more complicated data addressing.
If this option is on and files are archived with a password, "Wipe files" mode is enabled regardless of other options in "Delete mode" group.
There is no much sense to enable it directly in archiving dialog, because you can just turn on "Wipe files" instead. So this option is intended for use in compression profiles. If you prefer to always delete encrypted files securely, you can enable "Wipe files if password is set" in the default compression profile.
Store BLAKE2 file checksums. Available only for RAR 5.0 archive format.
File data integrity in RAR archive is protected by checksums calculated and stored for every archived file. By default, WinRAR uses CRC32 function to calculate the checksum. RAR 5.0 archive format also allows to select BLAKE2sp version of BLAKE2 hash function instead of CRC32.
CRC32 output is 32 bit length. While CRC32 properties are suitable to detect most of unintentional data errors, it is not reliable enough to verify file data identity. In other words, if two files have the same CRC32, it does not guarantee that file contents is the same.
BLAKE2 output is 256 bit. Being a cryptographically strong hash function, it practically guarantees that if two files have the same value of BLAKE2, their contents is the same. BLAKE2 error detection property is also more reliable than in shorter CRC32.
Since BLAKE2 output is longer, resulting archive is slightly larger, when this option is enabled.
If archive headers are unencrypted (Encrypt file names option was not set), checksums for encrypted RAR 5.0 files are modified using a special password dependent algorithm, to make impossible guessing file contents based on checksums. Do not expect encrypted file checksums to match usual CRC32 and BLAKE2 values.
If this option is enabled, WinRAR analyzes the file contents before starting archiving. If several identical files larger than 64 KB are found, the first file in the set is saved as usual file and all following files are saved as references to this first file. It allows to reduce the archive size, but applies some restrictions to resulting archive. You must not delete or rename the first identical file in archive after the archive was created, because it will make extraction of following files using it as a reference impossible. If you modify the first file, following files will also have the modified contents after extracting. Extraction command must involve the first file to create following files successfully.
It is recommended to use this option only if you compress a lot of identical files, will not modify an archive later and will extract an archive entirely, without necessity to unpack or skip individual files. If all identical files are small enough to fit into compression dictionary, solid archiving can provide more flexible solution than this option.
Supported for RAR 5.0 archives only.
RAR archives store every file header containing information such as file name, time, size and attributes immediately before data of described file. This approach is more damage resistant than storing all file headers in a single continuous block, which if broken or truncated would destroy the entire archive contents. But while being more reliable, such file headers scattered around the entire archive are slower to access if we need to quickly open the archive contents in a shell like WinRAR graphical interface.
To improve archive open speed and still not make the entire archive dependent on a single damaged block, RAR 5.0 archives can include an optional quick open record. Such record is added to the end of archive and contains copies of file names and other file information stored in a single continuous block additionaly to normal file headers inside of archive. Since the block is continuous, its contents can be read quickly, without necessity to perform a lot of disk seek operations. Every file header in this block is protected with a checksum. If WinRAR detects that quick open information is damaged, it resorts to reading individual headers from inside of archive, so damage resistance is not lessened.
Quick open record contains the full copy of file header, which may be several tens or hundreds of bytes per file, increasing the archive size by the same amount. This size increase is most noticeable for many small files, when file data size is comparable to file header. So by default, in "Add for larger files" mode, WinRAR stores copies of headers only for relatively large files and continues to use local headers for smaller files. Concrete file size threshold can depend on WinRAR version. Such approach provides a reasonable open speed to archive size tradeoff. If you prefer to have the maximum archive open speed regardless of size, you can use "Add for all files" to store copies of all file headers. If you need to have the smallest possible archive and do not care about archive open speed in different programs, set "Do not add" to exclude the quick open information completely.
If you wish to measure the performance effect of this option, be sure that archive contents is not stored in a disk cache. No real disk seeks are performed for cached archive file, making access to file headers fast even without quick open record.