it can be 1024 or 2048.
but need to take care of UTIL_HEAP_SZ:
In a normal backup ( or restore) when you do not specify how many
BUFFERS in the command, by default the 2 BACKBUFSZ and RESTBUFSZ will
be used. The Db need to have UTIL_HEAP_SZwith a size twice the value
of BACKBUFSZ +RESTBUFSZ
I mean if you have:
(BACKBUFSZ +RESTBUFSZ ) you needUTIL_HEAP_SZ
(1024 + 1024)=2048*2 -->5000
(2048 + 2048 )=4096*2 --> 10000
if you need to use 6 buffers of 2048 +1024 each one, then use a
UTIL_HEAP_SZ
=20000
if you manually specified them, you need to make sure you have enough UTIL_HEAP_SZ.
(backup buffer+RESTBUFSZ)*BUFFERS (default is 2) <=UTIL_HEAP_SZ
