Date: Sun, 24 Jan 2016 15:51:24 -0500 From: Kiriakos Georgiou <zebekias@gmail.com> To: freebsd-fs@freebsd.org Subject: zfs - reboot after panic Message-ID: <A4C07583-2AB4-436C-B5BE-34C952C3419B@gmail.com>
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Hello, I've been happily running a FreeBSD 10.1 fileserver (updated regularly via f= reebsd-update) with ZFS zvols served out via iscsi. Total RAM is 8G. For 2-= 3 months I regularly successfully run some heavy duty checksuming via unison= (it's kind of like rsync, but does bidirectional syncing). I recently upda= ted the OS to 10.1-RELEASE-p26, and soon after I started to consistently get= kernel panics when I run unison to sync certain files across my VMs: reboot after panic: I/O to pool 'zdata' appears to be hung on vdev guid ....= First I thought a bug must have been introduced, but after some googling I s= et my vfs.zfs.arc_max to 4G (50% of my ram) and hammered zfs via a massive u= nison sync. I monitored memory via top. ARC grew quickly to 4096M and stay= ed there. Free memory would slowly drop all the way to just under 1G but th= en it'd suddenly jump to over 2G, then slowly go down to 1G and jump to 2G a= gain so on. I suspect it was a RAM starvation issue that is now resolved by= tuning the ARC max. I've no idea why it started happening. I just wanted t= o share it with you. Does the "fix" make sense? Thanks, Kiriakos=
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