Each node must keep all blocks (transactions)?

[Frodo]

I install bitcoin client. It download block a few hours and occupies space 200MB for *.dat. It download today only 118 thousands small blocks because nowadays is only 112 transactions per hour. What will happen when the system spreads (which I wish him) and will be 10,even 100 more transactions? It is bottleneck of system?
Keeping all information on each node is incompatible with idea of p2p distributed system.

[BitterTea]

Nodes don't have to keep the full block chain, but the current implementation does. I believe the client supports a lightweight mode that only downloads block headers, but it's not enabled. There is also talk of an ultra lightweight mode that would only keep a portion of block headers, but would have to request additional information outside of the regular communication channels.

[Frodo]

Thanks, it will be good to have a lightweight mode in future. It will compatible with older clients?