On Thu, 9 Jun 2011, Emmanuel Noobadmin wrote:
I'm trying to resolve an I/O problem on a CentOS 5.6 server. The process basically scans through Maildirs, checking for space usage and quota. Because there are hundred odd user folders and several 10s of thousands of small files, this sends the I/O wait % way high. The server hits a very high load level and stops responding to other requests until the crawl is done.
If the server is reduced to a crawl, it's possible that you are hitting the dirty_ratio limit due to writes and the server has entered synchronous I/O mode. As others have mentioned, setting noatime could have a significant effect, especially if there are many files and the server doesn't have much memory. You can try increasing dirty_ratio to see if it has an effect, eg:
# sysctl vm.dirty_ratio # sysctl -w vm.dirty_ratio=50 Steve -- 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
