On Sat, 9 May 2015, Michael Eager wrote:
I am setting up a file server with CentOS 7. I'm seeing performance which is considerably slower than a similar server running CentOS 6.6. A 3Gb directory can be copied to/from the CentOS 6.6 server in about 50 seconds. The same directory takes about 270 seconds to copy to/from the CentOS 7 system.
I see the same performance difference with NFS mounted file systems or using scp, so it doesn't appear to be an NFS issue. The MTU on the NICs on both systems is 1500, and changing it to 6000 on the CentOS 7 system had no effect.
Anyone have any ideas what might cause this problem or how to fix it?
My first guess would be that stat() operations are the bottleneck. Are you using network authentication of some kind? If so, I'd try to identify differences in the authentication cache.
For instance, CentOS 6 may be using nslcd or nscd, while CentOS 7 is using sssd or nslcd. Repeated UID/GID lookups absent effective cacheing will slow things down as you describe.