From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Nowoczynski Date: Tue, 06 Nov 2007 14:57:50 -0500 Subject: [Lustre-devel] Checksum Algorithm In-Reply-To: <200711061130.32694.behlendorf1@llnl.gov> References: <200711061130.32694.behlendorf1@llnl.gov> Message-ID: <4730C73E.3080606@psc.edu> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org Brian, How does the crc mechanism work? I assume that the crc is done at the client, does the server verify the crc? Also are the crc's stored on disk? thanks, paul Brian Behlendorf wrote: > Roger, > > We've been running with checksums enabled in our release for some time now > and have seen the exact same impact on performance. In our case single node > performance is impacted but aggregate FS performance remains good when enough > clients are involved. We are tracking the performance issue under bug 13805 > and would love any input/insight you might have on the issue. > > Bug13805 > > My view on the issue is that it is madness to run with checksums disabled > and we need to investigate more efficient checksum algorithms. The current > crc32 algorithm may be too heavy weight but the simple XOR algorithm you > propose I fear is not strong enough. I've seen to many cases now of various > network components corrupting data in all sorts of interesting ways. > Happily we have a lot of other choices for algorithms to investigate. > > If you have the time I'd encourage you to investigate an assortment of > algorithms and see which work best. Making this a runtime option via > proc I think is also an excellent idea. > > > ------------------------------------------------------------------------ > > _______________________________________________ > Lustre-devel mailing list > Lustre-devel at clusterfs.com > https://mail.clusterfs.com/mailman/listinfo/lustre-devel >