Acronis True Image 2009 and earlier has failed in properly writing split file backups to large flash drives, 16gb and over, available since 2008. Using an NTFS file system on a 16gb the drive, a 12gb Windows OS partition backup divided into 4.7gb or smaller files, produces a prompt to insert new media after every file (not before the first, as configured off -- it just won't stay off for the rest of several files). The backup will run only with a single file unsplit backup with no opportunity to interupt with prompts. The backup can be copied from a hard drive to the flash, but not written directly by TrueImage in an unattended mode, without interupting prompts. The program does not properly recognize the properties of this media and treats it like a CD drive. Such splits are useful for subsequent copies of backups to other media such as DVD. (Note to put NTFS on a flash drive the "Policy" property of the drive in Windows must first be set to require dismounting before removal -- not the default; otherwise NTFS does not appear in the available formatting options.) A lengthy exchange with tech support has occurred over this, but appears to be going in circles -- another avenue is required.