Date: Wed, 4 Mar 1998 11:29:28 -0100 (GMT) From: Remy NONNENMACHER <remy@synx.com> To: Terry Lambert <tlambert@primenet.com> Cc: hackers@FreeBSD.ORG Subject: Re: Disk write caches Message-ID: <Pine.A32.3.91.980304110716.16895C-100000@rs1> In-Reply-To: <199803040313.UAA12989@usr05.primenet.com>
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On Wed, 4 Mar 1998, Terry Lambert wrote: > I would be very interested to see what the benchmarks on a machine > with soft updates would be with a disk with and without write > cacheing. > I tested cache benefits within disks. Write cache disabling lowered the perfs from 2 to 10 time depending on operations. RAIDying inside the kernel can be a good 'cheap' solution even if i prefer it external (for the same reasons as Mr Shapiro). What i humbly demand is that, for those able to plug an UPS on their machines, the performances DO NOT DEGRADE in the name of security. I want perfs, i need perfs. Okay, i spent a lot of money for good and fast disks, i know that loosing a disk on a CCD will require restoring 18GB and that it will takes me 2 or 3 hours but i prefer this eventuality rather than the certainty of 20% performances decrease. whatever you decide in the future, *PLEASE* make it optional. TIA. > In many repsects, write caching could be obsolete soon... ;-). > Not sure IMHO. Typical wait time before write starts is 20 to 50 ms or half the internal disk buffers. Far less than sync daemon. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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