Date: Fri, 26 Nov 2010 13:14:46 -0600 From: Adam Vande More <amvandemore@gmail.com> To: jhell <jhell@dataix.net> Cc: freebsd-stable@freebsd.org, Andriy Gapon <avg@freebsd.org> Subject: Re: More IO identification problems Message-ID: <AANLkTikGx%2B49We27AoH_9X_KHozzOzKyaQ%2BF_JPWuwSv@mail.gmail.com> In-Reply-To: <4CEFC534.2070904@DataIX.net> References: <AANLkTikdfTe797Ngw78CfqH1jZSX9TxeH%2Bum8MC_d-wx@mail.gmail.com> <4CEFB8F7.4080002@freebsd.org> <4CEFC534.2070904@DataIX.net>
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On Fri, Nov 26, 2010 at 8:33 AM, jhell <jhell@dataix.net> wrote: > > Perhaps it's some external component? > > E.g. hald is known to perform some disk/media checks every two seconds. > > > > As well syslod will also cause sync to happen prematurely when something > goes to log. > > syslog.conf(5): > *** > To ensure that kernel messages are written to disk promptly, > syslog.conf calls fsync(2) after writing messages from the kernel. > Other messages are not synced explicitly. You may prefix a pathname > with the minus sign, ``-'', to forego syncing the specified file > after every kernel message. Note that you might lose information if > the system crashes immediately following a write attempt. Neverthe- > less, using the ``-'' option may improve performance, especially if > the kernel is logging many messages. > *** > > This is obviously the old way of ensuring logs are written to disk > before crash but now ZFS is handled differently. Check to see if adding > '-' to your syslog entries relieves that problem as ZFS will do the > right thing to ensure your data is written to disk. > Thanks, avg and jhell. hald was indeed the culprit, and a "hal-disable-polling --device /dev/cd0" has restored my sanity. I never liked the cd notifications anyway. -- Adam Vande More
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