From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sat, 20 Sep 2008 15:18:21 +0200 From: Lars Ellenberg To: Morey Roof Subject: Re: [Drbd-dev] New Features Message-ID: <20080920131821.GB16149@racke> References: <48D3378E.3020201@gmail.com> <20080919155343.GD9779@soda.linbit> <91a37e890809190919g5a746367g54e76d36e1a825f6@mail.gmail.com> <20080919221339.GB15916@soda.linbit> <48D42783.1050403@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <48D42783.1050403@gmail.com> Cc: drbd-dev@lists.linbit.com List-Id: Coordination of development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Sep 19, 2008 at 04:28:19PM -0600, Morey Roof wrote: > The first item on the list is a write back cache. Now don't run > screaming to hills yet. In our setup we have the two nodes in two > different buildings which are feed by different power supplies from the > city grid. The machines themselves have dual power supplies which each > power supply going to it's own UPS and circuit. So, we have a good > redundant power supply setup. So, I was thinking about creating a > caching system in DRBD to allow for dedicating some of the server's RAM > to a large read/write-back cache. In the event of communication failure > between the peers I wanted it to flush the entire cache and then run in > write-through mode and move back to write-back mode after communication > is present again and the resync is finished. > > So that is the basic idea. I was thinking about having it use the > ramdisk system so that you can specify a device that is used as the > cache. The reason I was thinking about this is that if you happen to > purchase one of those Gigabyte ram HDD that is just like a large battery > backed write cache you could set it as the cache device as well. > > What are your thought? something I though of myself already, but nothing for the curren drbd architechture. I sent you my Linux-Kongress 2008 paper off list, where I scetch what I have in mind for the future. I'd put in a link here, if I had it online already. though I did not mention it, a (possibly non-volatile) ram disk would fit in pretty well as the log device. let me know what you think. -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. __ please don't Cc me, but send to list -- I'm subscribed