Date: Sat, 16 Mar 2013 13:49:27 -0500 From: Tim Daneliuk <tundra@tundraware.com> To: FreeBSD Mailing List <freebsd-questions@freebsd.org> Subject: NFS Performance: Weirder And Weirder Message-ID: <5144BEB7.3090906@tundraware.com>
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This is really weird. A FreeBSD 9.1 system mounts the following: /dev/ad4s1a 989M 625M 285M 69% / devfs 1.0k 1.0k 0B 100% /dev /dev/ad4s1d 7.8G 1G 6.1G 14% /var /dev/ad4s1e 48G 9.4G 35G 21% /usr /dev/ad4s1f 390G 127G 231G 35% /usr1 /dev/ad6s1d 902G 710G 120G 86% /usr1/BKU /usr1/something (under ad4s1f) and /usr1/BKU (all of ad6s1d) are exported for NFS mounting on the LAN. I have tested the speeds of these two drives locally doing a 'dd if=/dev/zero ....'. Their speeds are quite comparable - around 55-60 MB/s so the problem below is not an artifact of a slow drive. The two mounts are imported like this on a Linux Mint 12 machine: machine:/usr1/BKU /BKU nfs rw,soft,intr 0 0 machine:/usr1/shared /shared nfs rw,soft,intr 0 0 Problem: When I write files from the LM12 machines to /BKU the writes are 1/10 the speed of when writing to /shared. Reads are fine in both cases, at near native disk speeds being reported. Someone here suggested I get rid of any symlinks in the mount and I did that to no avail. Incidentally, the only reason I just noticed this is that I upgraded the NIC on the FreeBSD machine and the switch into which it connects to 1000Base because the LM12 machine had a built in 1000Base NIC. I also changed the cables on both machines to ensure they were not the problem. Prior to this, I was bandwidth constrained by the 100Base so I never saw NFS performance as an issue. When I upgraded, I expected faster transfers and when I didn't get them, I started this whole investigation. So ... I'm stumped: - It's not the drive or SATA ports because both drives show comparable performance. - It's not the cables because I can get great throughput on one of the NFS mountpoints. - It's neither NIC for the same reason. Does anyone: A) Have a clue what might be doing this B) Have a suggestion how to track down the problem Thanks, -- ---------------------------------------------------------------------------- Tim Daneliuk tundra@tundraware.com PGP Key: http://www.tundraware.com/PGP/
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