Date: Thu, 17 Jan 2002 13:50:05 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/33941: /usr/sbin/dev_mkdb dumps core Message-ID: <200201172150.g0HLo5A91363@freefall.freebsd.org>
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The following reply was made to PR bin/33941; it has been noted by GNATS.
From: Matthew Dillon <dillon@apollo.backplane.com>
To: Ryan Dooley <dooleyr@missouri.edu>
Cc: Sheldon Hearn <sheldonh@starjuice.net>,
<bug-followup@FreeBSD.ORG>
Subject: Re: bin/33941: /usr/sbin/dev_mkdb dumps core
Date: Thu, 17 Jan 2002 13:45:07 -0800 (PST)
: Uh oh,
:
: I have a server then with 65536/8192 (bs,fr) for a 953GB
: fiber channel raid. I've not noticed anything bad off hand
: (it was CVSup'd on Saturday around midnight CST.
That should be fine.
: This actually concearns me more than my workstation :-)
:
: We changed the block/frag size to speed up file system checks
: when we had to fsck that partition (which holds 41000+ user
: home directories). We went from fsck's taking about 120 minutes
: to 15 minutes which we drastically needed.
:
: I have had reports that reads over NFS (a client running a program
: on a file (SAS data)) took two or three attempts to initialy
: access the file before sas ran with it. Sounded like a NFS cache
: issue, but I couldn't reproduce the error myself. (AIX client to
: FreeBSD server).
:
: As the semester is about to start, I can't reformat that array
: right now.
:
: Ryan
This would depend on the NFS block size, which is independant of the
filesystem block size. Even a standard NFS block size of 8K requires
7 IP fragments to construct a packet (with a standard ethernet's MTU).
A larger NFS block size would result in even more fragments and
potentially overload the client's packet buffers.
It is usually possible to mitigate NFS 'packet storm' issues by using
TCP NFS mounts rather then UDP.
-Matt
Matthew Dillon
<dillon@backplane.com>
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