To simplify, BitTorrent breaks files up into blocks, checksums eachblock, and then has all of the clients (the peers) swap blocks back andforth. The checksums for all the blocks are in the .torrent metainfofile that each client has, so you know when you get a bad copy of ablock (and as a side effect, a malicious client can't serve you trojandata).

(One might think that trojan data would be relatively harmless. ButBitTorrent is used to distribute things that

This is a quick and, unfortunately, overdue update. The last timearound , I wrote about how we had discoveredthe zfs_arc_min ZFS tuning parameter, so that we could set a minimumARC size so that it would not shrink too much.

Here is an important update: don't do this.

Since we set a minimum ARC size, we have had mysterious but ultimatelyconsistently reproduceable system failures under load. The consistentway to kill our (then) lead NFS fileserver was that after at