Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uwm.edu!psuvax1!hydra!droms From: droms@regulus.bucknell.edu (Ralph E. Droms) Newsgroups: comp.protocols.nfs Subject: Re: NFS performance Message-ID: Date: 14 Jun 91 13:24:49 GMT References: <1991Jun13.164017.29944@Firewall.Nielsen.Com> <625@appserv.Eng.Sun.COM> <1991Jun13.234448.16172@Firewall.Nielsen.Com> Sender: news@hydra.bucknell.edu Reply-To: droms@bucknell.edu Organization: Bucknell University, Lewisburg, Pa. Lines: 21 In-reply-to: kdenning@genesis.Naitc.Com's message of 13 Jun 91 23:44:48 GMT In article <1991Jun13.234448.16172@Firewall.Nielsen.Com> kdenning@genesis.Naitc.Com (Karl Denninger) writes: > >If the server ACKs the data before writing it to disk, there is a window >during which the server can crash. The data is then lost. How does this differ from the standard "Unix" way of doing file I/O, which returns a successful reply from a write call before the data is safely on disk? If you write data, get back a "ACK" (or good return value) the data isn't necessarially on disk -- it could be in the buffer cache. If the machine crashes before the data is flushed you lose. I think the difference lies in the feedback to the user. If the local UNIX box crashes, the user is aware "something is wrong" immediately. If the server crashes and reboots, the data can be lost silently... -- - Ralph Droms Computer Science Department droms@bucknell.edu 323 Dana Engineering Bucknell University (717) 524-1145 Lewisburg, PA 17837