Good afternoon!
such a problem:
bought for the ROS two Dell servers PE1950 with SAS disk controller.
Of course that SAS is not supported RouterOS did not think.
Accordingly, the question - if you put the ROS on a USB flash drive 8 Gb, how much will its resource last? I understand that ROS uses the disk just to boot the OS and in the future it is not used?
The first server with the DOS is used as the BGP router, and the second server as BRAS.
AFAIK you cannot install ROS onto USB sticks, unless something has changed over the past years (I haven’t tried in a long time).
Other than that, ROS will make very few to a lot of writes, depending on your configuration.
ROS does write to disk occasionally, amount of writes heavily depend on configuration.
I wouldn’t rely on consumer-grade USB flash drives. My experience is that some don’t last very long even if they are mostly used for reading. In your situation I’d consider running ROS in virtualized environment instead of bare metal. In that case VM takes care of hardware itself and presents “guest OS” (ROS in your case) some generalized hardware instead. In turn it consumes some resources … so it’s not simple win-win situation.