USB persistence files allow you to save any changes you make to your network login/password, desktop arrangement, software, etc. after you logout. You can make your own backup "snapshot" USB safe copies of your persistence files or, if necessary, replace a crashed persistence file with one from the BACKUP LINK above.
Ubuntu-based distros Xubuntu, Zorin and Peppermint use standard casper-rw files placed in the distro's respective multiboot home directories. The default 512MB size is more than enough for basic use. It is not enough for making major software updates and additions. If you try, you may run out of persistent storage space and your distro will crash. In that case, you can (1) replace your crashed casper-rw file with one from your own backups (or from the backup link) or (2) run create-ubuntu-save-file.exe to make a new and larger casper-rw file to replace your old crashed casper-rw file. Note that method two loses both Lite Speed and personal changes.
Puppy Linux distros LxPupTahr and Simplicity were given smaller 256MB SAVE files. This is because Puppy distros were designed for USB and work differently. New software "pets" (.sfs files) are normally added as new files independent of the SAVE files. Software added as .txz or .tgz files is also independent of SAVE files. However, non-pet installed software added via the common .deb method is not independent and may cause your USB Puppy distro to crash. In the event of a crash, just as with Ubuntu-based distros, replace a crashed SAVE file (lxtahrsave.2fs or slackosave.2fs) with one of your own backups or one from the BACKUP LINK.
Porteus KDE was given a very small default 64MB (.dat) SAVE file. Even more than Puppy, Porteus was designed for USB use. From the beginning, new users customize the selection of software before downloading. If you plan to do major adding or updating of software, you can expand the SAVE file size while running Porteus. If necessary, however, you can replace your porteus3.1.dat file with the one from your own backups or from the BACKUP LINK.
SliTaz is tiny but surpisingly well featured (except no default wifi drivers). We use SliTaz for viewing Lite Speed's offline distro documentation using it's home=usb parameter. SliTaz does not use a persistent "file". Instead, it creates two files, .provd.124 and .provn.124 plus a user (/tux) directory in the main (root) directory of your USB flash drive. In the event of a serious crash, you can replace those files and /tux directory with the backup ones.
OpenElec XBMC has a 512MB SAVE file /storage in the main (root) directory of the USB flash drive.
AndroidX86 5.0.2 was unable to use a persistence file. You can only try it on USB and/or install to hard drive. The TinyCore distro included with Lite Speed is mostly for non-GUI command-line Linux utility and rescue use - no persistent file. The PupRescue distro, by default, has no persistence although it could be added.
|[ OpenElec XBMC ]||524288 KB /storage|
|[ SliTaz ]||7.4 KB /tux + /.provd.124 + /.provn.124|
|LxPupTahr-15.03.1-pae:||262144 KB lxtahrsave.2fs|
|Peppermint-5-20140623-i386:||512000 KB casper-rw|
|Porteus-KDE4-v3.1-i486:||65536 KB porteus3.1.dat|
|Simplicity-Net151:||262144 KB slackosave.2fs|
|xubuntu-14.10-desktop-amd64:||512000 KB casper-rw|
|zorin-os-9-lite-32:||512000 KB casper-rw|