From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: HBA Adaptor advice Date: Fri, 20 May 2011 15:12:56 -0500 Message-ID: <4DD6CB48.6050701@hardwarefreak.com> References: <4DD50C89.8060006@wildgooses.com> <20110520020853.GC4759@bitfolk.com> <4DD61948.8050302@wildgooses.com> <4DD65C18.5090804@gmail.com> <20110520200100.GF4759@bitfolk.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110520200100.GF4759@bitfolk.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 5/20/2011 3:01 PM, Andy Smith wrote: > It's a shame; maybe there will be disks with battery-backed cache > one day. You'll never see a cache DRAM BBU built into a drive. If this *concept* were to be implemented it would be done with flash and a capacitor instead of a BBU. The capacitor would be sized to hold just enough juice to power the ASIC, flash chip, and related circuitry, and write the cache DRAM contents to the flash chip after sensing power to the card has been lost. Many higher end RAID cards already have flash backup of the cache DRAM in addition to, in instead of, a BBU. -- Stan