time machine backup to flash drive

BobTedescoJr wrote:

Can I use a flash (or thumb) drive as a time machine backup?

Sure, but it had better be a very big thumbdrive. In an ideal world it would be 3 times as large as the amount of disk space you are ultimately going to be using on your Mac's boot disk. 2 times as much would be fine, you just have less backup history, depending on how often you modify files (and OS X modifies files0. 1-for-1 in size is not really good, as Time Machine wants to maintain older backups and would be spending a lot of time purging before it could write updated files.

Format the device for HFS+ (Mac OS Extended (Journaled)) and point Time Machine at the device.

According to Apple, it is essential to the operation of Time Machine that the Time Machine backup device is indexed by Spotlight. This will occur even when you place the Time Machine drive in the Spotlight Privacy panel as a drive to omit from said indexing.

If you deliberately want to slow your Mac to a crawl, use a USB stick, or SDXC card as the target Time Machine device. Not only will it take forever for a Time Machine backup to finish, but combine that with the fact that Spotlight might get impatient waiting for the backup to finish, and simultaneously add additional I/O and CPU delays by indexing that drive — in competition with TIme Machine for machine resources.

And Bob Harris has addressed the other issues of using a limited capacity device for Time Machine.

VikingOSX, In theory, BobTedescoJr could have a USB3 capable Mac and a high performance USB3 thumb drive. And since I only have USB2 based Macs (it is my Wife that has the newer hardware 🙂), I agree with your assessment of USB Thumb Drive and SD card speeds on my Macs.