USB flash drive: Difference between revisions

[[Optical storage devicesdevice]]s are among the cheapest methods of mass data storage after the hard drive. They are slower than their flash-based counterparts. Standard 12 cm optical discs are larger than flash drives and more subject to damage. Smaller optical media do exist, such as [[business card CD]]-Rs which have the same dimensions as a credit card, and the slightly less convenient but higher capacity 8 cm recordable CD/DVDs[[MiniCD]] and [[MiniDVD]]. The small discs are more expensive than the standard size, and do not work in all drives.

[[Universal Disk Format]] (UDF) version 1.50 and above has facilities to support rewritable discs like sparing tables and virtual [[File Allocation Table|allocation tables]], spreading usage over the entire surface of a disc and maximising life, but many older operating systems do not support this format. Packet-writing utilities such as [[DirectCD]] and [[InCD]] are available but produce discs that are not universally readable (although based on the [[Universal Disk Format|UDF]] standard). The [[Mount Rainier (packet writing)|Mount Rainier]] standard addresses this shortcoming in CD-RW media by running the older file systems on top of it and performing defect management for those standards, but it requires support from both the CD/DVD burner and the [[operating system]]. Many drives made today do not support Mount Rainier, and many older operating systems such as Windows XP and below, and Linux kernels older than 2.6.2, do not support it (later versions do). Essentially CDs/DVDs are a good way to record a great deal of information cheaply and have the advantage of being readable by most standalone players, but they are poor at making ongoing small changes to a large collection of information. Flash drives' ability to do this is their major advantage over optical media.