From owner-freebsd-questions Thu Dec 23 6: 6:54 1999 Delivered-To: freebsd-questions@freebsd.org Received: from linux.ssc.nsu.ru (linux.ssc.nsu.ru [193.124.209.130]) by hub.freebsd.org (Postfix) with SMTP id 7B15F14DC2 for ; Thu, 23 Dec 1999 06:06:33 -0800 (PST) (envelope-from danfe@inet.ssc.nsu.ru) Received: (qmail 14453 invoked from network); 23 Dec 1999 14:06:19 -0000 Received: from inet.ssc.nsu.ru (62.76.110.12) by hub.freebsd.org with SMTP; 23 Dec 1999 14:06:19 -0000 Received: from localhost (danfe@localhost) by inet.ssc.nsu.ru (8.8.7/8.8.7) with ESMTP id UAA15212; Thu, 23 Dec 1999 20:04:22 +0600 Date: Thu, 23 Dec 1999 20:04:22 +0600 (NOVT) From: "Alexey N. Dokuchaev" To: Kent Stewart Cc: freebsd-questions@FreeBSD.ORG Subject: Re: when is it safe to use the 0xa0ffa0ff disk flags? In-Reply-To: <386182DA.660B55ED@3-cities.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Hi! > CDC (now out of the business) had a hard drive called a Hydra. It was > a full height 8" HD that ran 9.6MB/s in 1988. It was also very > expensive at $250,000 US. Cray striped them together to create what > they called a DD40. It had 16 Hydras and had a total of 20GB. By > striping 4 together, Cray would get 20MB/s when they were hung on the > 100MB/s data channel. When our benchnmark was run on a system with the > Hydras for main storage, the throughput basically doubled. The Cray > XM/P had 2x the throughput of the CDC-990. The 990 was a dinosaur and > represented the end of big iron. It filled the room where as the Cray > looked like the what was left of the volcano in "Close Encounters of > the Third Kind". I think the 8" FH HD's were all replaced by HH 5.25" > HD's, which looked pretty puny mounted in the center of the Hydra's > bay. The cooling requirements probably dropped 10KVA :). The effect of > the Hydra on the benchmark was enormous. This the benchmark that I > told you about writing behind was so important. The benchmark ran > almost twice as fast when write behind caching was used. I think > SOFTUPDATES produce an imporovement that helps for similar reasons. Is there anywhere where I can read more about it? ./danfe To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message