Date: Wed, 18 Jan 2012 02:21:35 +1100 From: Aristedes Maniatis <ari@ish.com.au> To: Ken Smith <kensmith@buffalo.edu> Cc: freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: dumpdev default Message-ID: <4F1591FF.2000902@ish.com.au> In-Reply-To: <1326812852.24361.8.camel@bauer.cse.buffalo.edu> References: <4F15253E.7070404@ish.com.au> <1326812852.24361.8.camel@bauer.cse.buffalo.edu>
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On 18/01/12 2:07 AM, Ken Smith wrote: > On Tue, 2012-01-17 at 18:37 +1100, Aristedes Maniatis wrote: >> The manual states that dumpdev "AUTO is the default as of FreeBSD >> 6.0" [1] >> >> However: >> >> # uname -a >> FreeBSD xxxxxx 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Tue Jan 3 07:46:30 >> UTC 2012 root@farrell.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC >> amd64 >> >> # grep dumpdev /etc/defaults/rc.conf >> dumpdev="NO" # Device to crashdump to (device name, AUTO, or NO). >> savecore_flags="" # Used if dumpdev is enabled above, and present. >> >> >> It looks like NO is still the default. Is there a reason why this >> should not be turned on even for production machines? I haven't read >> about any side effects, but it seems to be off by default for some >> reason. >> >> >> Please cc me on any responses since I'm not currently subscribed. >> >> Cheers >> Ari > > If you use bsdinstall(8) to install a machine from scratch it explicitly > asks you about whether you want crash dumps enabled or not. > > As long as you're aware that the crash dumps are happening and know that > you might need to clean up after them (remove stuff from /var, etc) > there are no dangers. You just need to make sure wherever the crash > dumps will wind up going (/var by default) has enough space to handle > both the crash dumps and anything else the machines need to do. We > currently have no provision for preventing crash dumps from filling up > the target partition. > > I keep advocating for the conservative side of this issue, preferring > that crash dumps be an opt-in setting until we have infrastructure in > place to prevent them from filling the target partition. I still > picture there being people out there who don't know what crash dumps > are, wouldn't know they might need to clean up after them, and may > be negatively impacted if the target partition wound up full without > them knowing why. > Thanks Ken. That is very clear. If you have time, please update the documentation with that answer too since others are likely to be confused by what I found there which is incorrect and incomplete. Also, for ZFS users, I assume that the first swap disk will be default? So this is another consideration when sizing up swap partitions as compared to the size of memory installed. Thanks Ari -- --------------------------> Aristedes Maniatis ish http://www.ish.com.au Level 1, 30 Wilson Street Newtown 2042 Australia phone +61 2 9550 5001 fax +61 2 9550 4001 GPG fingerprint CBFB 84B4 738D 4E87 5E5C 5EFA EF6A 7D2E 3E49 102A
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