uncommited block status when checkpoint occurs

[ganga]

when database buffer get filled or check point occurs content of database buffers(dirty buffers)are written to datafiles.

As i know dirty buffers are :-modified or commited blocks..

My question is
1)how long that modified blcoks(not commited) blocks will be there in datafile..
2)will oracle keeps all modified and commited blcoks in the datafile throughout the lifespan or flushes uncommited blocks from datafile by triggering certain events..

[pando]

1) when there are checkpoints (complete and incremental), when free buffer is needed and a threshold has been searched by dbwr, when dbwr awakes which is around every 3 seconds

2) Oracle can leave your datafiles with dirty blocks, i.e your datafile scan have uncommitted data

[DaPi]

Originally posted by pando
1) . . . . when dbwr awakes which is around every 3 seconds

Do you have a ref for that pando? (I thought it was lgwr that had the every 3 second wake-up call.)

PS: . . . and ckpt updating the control files with the ckpt status every 3 secs.