Date: Thu, 02 Apr 2015 10:50:40 -0500 From: Rick Romero <rick@havokmon.com> To: Adam Guimont <aguimont@tezzaron.com> Cc: freebsd-fs@freebsd.org Subject: Re: NFSD high CPU usage Message-ID: <20150402105040.Horde.DpcVnMHXCV_MvaXmGcnU1g8@www.vfemail.net> In-Reply-To: <551D5CBC.1010009@tezzaron.com> References: <20150401154314.Horde.e_w-9XEJOaa4SwYyNLlttA3@www.vfemail.net> <551D5CBC.1010009@tezzaron.com>
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Quoting Adam Guimont <aguimont@tezzaron.com>: > Rick Romero wrote: >> Does your ZFS pool have log devices? >> How does gstat -d look? >> >> If the drives are busy, try adding >> vfs.nfsd.async: 0 > > No log devices but the disks are not busy when this happens. > > I have an atop snapshot from the last time it happened: > http://pastebin.com/raw.php?i=LQjbKTXR Are the disks busy before it happens? I'm far from an expert, but when running ZFS with NFS, I've had a lot of issues. My final resolutions were to turn ASYNC off and have log devices and I even have SSD volumes now. Otherwise under load the NFS server gets hung up. It never seemed to happen on UFS, but due to the number of small files I have, ZFS provides the best backup functionality. I'm now trying to move all functions from NFS (to more TCP client/server). You have different info than I've gathered, and it might be because of usage. I actively use the system that I've seen NFS dump on, so I see the slowness beginning. Once NFS dies, the drive load goes back to normal. I wonder, if maybe you are just managing a system for others, and you don't see it until after the fact? Just a thought based on my limited experience. Rick
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