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Xref: sserve comp.unix.bsd:12671 comp.unix.wizards:30890 comp.sys.sun.apps:4869 comp.sys.sun.misc:9682 Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!agate!CS.Berkeley.EDU!eric From: eric@CS.Berkeley.EDU (Eric Allman) Newsgroups: comp.unix.bsd,comp.unix.wizards,comp.sys.sun.apps,comp.sys.sun.misc Subject: Re: checkpointing software for UNIX or SunOS Date: 23 Sep 1993 14:41:57 GMT Organization: UC Berkeley Mammoth Project Lines: 19 Sender: eric@mastodon.CS.Berkeley.EDU (Eric Allman) Distribution: world Message-ID: <27scjl$qjc@agate.berkeley.edu> References: <TMB.93Sep23012442@arolla.idiap.ch> <VIXIE.93Sep22202934@gw.home.vix.com> Reply-To: eric@CS.Berkeley.EDU NNTP-Posting-Host: mastodon.cs.berkeley.edu In article <VIXIE.93Sep22202934@gw.home.vix.com>, vixie@gw.home.vix.com (Paul A Vixie) writes: |> I've seen several "undump"-like facilities built into shells and kernels to |> provide checkpointing, but the user community that can benefit from them is |> small and getting smaller since almost all long-running processes have |> network connections open to various servers (even implicit ones such as a |> connection to kerberos or hesiod or DNS), or they have files open to system |> configuration files (/etc/services, /etc/passwd) which might not be the same |> size and layout after a restart. |> |> Processes that need checkpointing generally have to implement it themselves, |> as Sendmail does with its frozen configuration file and as GNU Emacs does |> with its "undump" mechanism. It's worth pointing out that this is VERY hard to get right and even harder to do portably. For example, there can be system routines that have resources open that you know nothing about. I've taking the freeze file out of sendmail entirely -- it was more trouble than it was worth. eric