Just a followup ... Neil said he has never seen disks corrupt spontaneously. I'm just making the rounds of checking the daily md5sums on one group of machines with a view to estimating the corruption rates. Here's one of the typical (one bit) corruptions: doc013:/usr/oboe/ptb% cmp --verbose /tmp/cardmgr /sbin/cardmgr 1641 22 52 /tmp has the correct version, copied from elsewhere. I haven't checked yet to see if it's a memory error or a disk error. I'll reboot the whole set later. But this machine has been up only 2 days so it's unlikely to have accumulated errors, and cardmgr will not have been used apart from being md5summed. There are 30 machines in this set. I may have more stats when I have finished. Peter - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html