Debugging NFS issues can sometimes be a chore, especially when you are dealing with busy NFS servers. Tools like nfswatch and nfsstat can help you understand what operations your server is servicing, but sometimes you need to get into the protocol guts to find out more info. There are a couple of ways you can [...]
Most admins have probobably encountered a situation where someone says “hey this really bizarre thing is occurring.” Whenever I am approached to look at these types of issues I will typically start by jumping on my systems and reviewing system, network and performance data. Once I’ve verified those are within normal levels I will begin [...]
Linux NFS server implementations export a number of statistics through the /proc file system. The nfsstat utility can parse this file and display various performance counters, and the data that is displayed comes from the /proc/net/rpc/nfsd proc entry: $ cat /proc/net/rpc/nfsd rc 0 2585 290 fh 0 0 0 0 0 io 1069882 10485760 th [...]
As an admin, there is nothing worse that the feeling you get when you determine you are dealing with file system corruption. Wether it’s a lost inode or a corrupted superblock, I always get a big knot in my stomach when I figure out that corruption exists. With modern file systems like ZFS it’s trivial [...]
Storage management, the joys! Storage administration is one of those tasks that every admin does, and depending on your growth it may be something that consumes a lot of your time. If your servers are connected to a Fibre channel or iSCSI SAN, you probably need to periodically poke your systems to see new storage [...]
I’ve been fascinated with I/O and file system performance for years, and chose prefetch.net as my domain name after reading about pre-fetching algorithms in the book UNIX file systems (a great book that I need to read again). Since most applications access data that is not laid out sequentially on a hard drive platter, seek [...]
