From owner-freebsd-questions Wed Oct 11 17:02:11 1995 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id RAA23921 for questions-outgoing; Wed, 11 Oct 1995 17:02:11 -0700 Received: from who.cdrom.com (who.cdrom.com [192.216.222.3]) by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id RAA23916 for ; Wed, 11 Oct 1995 17:02:09 -0700 Received: from bud.indirect.com (straka@bud.indirect.com [165.247.1.10]) by who.cdrom.com (8.6.12/8.6.11) with ESMTP id RAA04110 for ; Wed, 11 Oct 1995 17:01:16 -0700 Received: (from straka@localhost) by bud.indirect.com (8.6.12/8.6.6) id RAA00168; Wed, 11 Oct 1995 17:00:44 -0700 Date: Wed, 11 Oct 1995 17:00:38 -0700 (MST) From: "Richard S. Straka" To: questions@FreeBSD.org Subject: NFS performance Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-questions@FreeBSD.org Precedence: bulk I have set up my 486DX-100 as an NFS server for a network that currently has PCNFS running on a Pentium-100 and a 386DX-25 (all machines are using Intel EtherExpress Boards). I am using a FreeBSD-stable kernel which I downloaded from wcarchive.cdrom.com on approx 1 Oct 95. The server filesystem is mounted on the Pentium with rsize=8192 and wsize=8192. While reading from the NFS server, the Pentium can achieve 600-700KB/sec, nearly the speed of the ether. While writing to the server, however, the speed of the tranfers seem to be limited to about 100KB/sec with alot of disk thrashing occuring on the server. While running SYSTAT on the server, I noticed that the processor idle time is still greater than 50% but the disk transfer rate is around 400KB/sec with 40-50 seeks/sec. Why is the disk transfer rate 4 times the file transfer rate between the client and the server and why so many seeks? I have used NETSTAT to verfy that I am not dropping any UDP packets. In sys/nfs/nfs_serv.c in the kernel code there is a compiler directive NFS_ASYNC. When I compile the kernel with this directive set, the file transfer speed while writing to the server increases to about 400KB/sec (still not the 600-700KB/sec realized while reading from the server) and the apparent disk thrashing is gone (400KB/sec disk transfers with 10-20 seeks/sec). This change, however, has made the server file system very vunerable to system crashes. Two power outages (even after the system had been idle for several minutes - no nfs transfers) have resulted in broken filesystems (more than 100 bad INODES). In both instances, the file system was unrecoverable (FSCK core dumped) and a new filesystem had to be created on the drive. Are there any suggestions for improving the speed of the clients writing to the server while still maintaining a reasonable tolerance to system crashes? Any help would be greatly appreciated. Thanks in advance. My e-mail address is straka@indirect.com.