NFS Performance: Weirder And Weirder
Mehmet Erol Sanliturk
m.e.sanliturk at gmail.com
Sat Mar 16 21:20:34 UTC 2013
On Sat, Mar 16, 2013 at 11:49 AM, Tim Daneliuk <tundra at tundraware.com>wrote:
> 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
> 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
> 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
> - It's not the cables because I can get great throughput on one of the NFS
> - 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
> Tim Daneliuk tundra at tundraware.com
> PGP Key: http://www.tundraware.com/PGP/
With respect to your mount points : /usr1 is spanning TWO different
/dev/ad4s1f 390G 127G 231G 35% /usr1
/dev/ad6s1d 902G 710G 120G 86% /usr1/BKU
because /usr1/BKU is a sub-directory of /usr1 .
If you create a new directory , for example /usr2 , and /usr2/BKU , and
using this new separate directory for sharing , such as :
/dev/ad6s1d 902G 710G 120G 86% /usr2/BKU
machine:/usr2/BKU /BKU nfs rw,soft,intr 0 0
will it make difference ?
Mehmet Erol Sanliturk
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