On 2/1/2010 9:03 AM, Charles Curley wrote: > When I run fairly disk intensive tasks, like copying tens of gigabytes > to this machine, it slows to a crawl. Disk I/O slows down by two > orders of magnitude. >
Linux tends to use disk cache as much as possible, so until you start performing disk operations that fill all of the available RAM for the disk cache, things will appear snappier. While you are performing your disk operations, try watching 'vmstat 2' under the 'wa' (IO wait) to see what percentage of the CPU time is being spent waiting for IO. This number should remain as close to zero as possible. If the IO queue is so backed up that things aren't being handled prompty, then you will quickly notice IO based apps will begin to crawl. Adding more RAM usually helps with IO issues, as more of the disk can be cached to RAM. Also check 'smartctl -a /dev/sda' and check to see if the error rate is increasing rapidly. If the disk is spending it's time recovering from failures, this would decrease the throughput, and also indicates that the drive is probably going bad. /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
