Date: Fri, 18 Nov 2005 18:24:27 -0800 (PST) From: nmh <drumslayer2@yahoo.com> To: Mikhail Teterin <mi+mx@aldan.algebra.com>, questions@freebsd.org Subject: Re: throttling NFS writes Message-ID: <20051119022428.51823.qmail@web32904.mail.mud.yahoo.com> In-Reply-To: <200511181924.17282.mi%2Bmx@aldan.algebra.com>
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--- Mikhail Teterin <mi+mx@aldan.algebra.com> wrote: > Hi! > > We have an unusual problem with NFS writes being > _too fast_ for our good. > > The system is accepting database dumps from > NFS-clients and begins compressing > each dump as soon, as it begins arriving (waiting > for more via kevent, if > needed). > > The NFS-clients (database servers) run on slow Sparc > processors and can not be > bothered to compress their data... > > The setup works quite well, if the to-be compressed > data is still in memory, > when the compressor gets to it. > > "Unfortunately", those Sparc systems have rather > fast I/O rates and manage to > write their dumps faster, than the compressor can > compress it. When this > happens, the overall performance of the backup > script goes down through the > floor :-(, because it forces the disk to read the > middle of a file (for > compression), while data keeps arriving (from the > NFS-client) at the end of > it... > > So we'd like to stall the client's dumping, so that > the compressor can keep > up. Short of limiting NFS-bandwidth via ipfw, is > there a way to control NFS > speed dynamically? > > The uncompressed dumps are _huge_, although they > compress very well. So we can > not just accept all of them first and then start > compressing -- we don't have > enough room. There is enough to keep about 3 > full-dumps worth of compressed > data, but even a single uncompressed full dump would > not fit... > > -mi I'm not sure if this will help you but long ago there was a problem with reads and writes being too fast and we used to use a mount option to slow things down to help. server:/dir/dir /localdir/mountme nfs rw,-w=1024 ...etc #man mount_nfs sets the write data size to the specified value... Again not sure if this will help but thought I would suggest it. Nmh _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org" > The Large Print Giveth And The Small Print Taketh Away -- Anon __________________________________ Yahoo! FareChase: Search multiple travel sites in one click. http://farechase.yahoo.com
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