Scott McClanahan wrote: > On Mon, 2007-05-14 at 10:55 -0400, Ruslan Sivak wrote: > >> Steve Huff wrote: >> >>> On May 14, 2007, at 10:25 AM, Ruslan Sivak wrote: >>> >>> >>>> Steve Huff wrote: >>>> >>>> If you set up a third box to be the shared storage, doesn't that now >>>> become the single point of failure? >>>> >>> Short answer: maybe. :) >>> >>> Longer answer: If you set up your shared storage according to >>> upstream's guidelines, as described in the documentation >>> (http://mirror.centos.org/centos/4/docs/html/rh-cs-en-4/ch-hardware.html#TB-HARDWARE-NOSPOF), >>> then you provide at least two channels of communication between each >>> component in the cluster. In addition, you choose a platform for >>> shared storage that provides some redundancy of its own, whether it's >>> multi-controller HW RAID, or multiple storage nodes on a SAN, or what >>> have you. >>> >>> CS/GFS operates under the assumption that your shared storage is >>> fault-tolerant; its job is to make your services fault-tolerant. Is >>> the recommended "no single point of failure" configuration proof >>> against your data center burning down, or against a madman with an >>> axe? Unlikely. Will it allow you to host services in a way that is >>> considerably more robust and flexible than hosting them on a single >>> box? Yes. >>> >>> -Steve >>> >>> >> I am currently running a redundant environment on windows by having 2 >> boxes with apache and having the data (images) be synced over >> automatically between servers using FRS (File Replication Service). >> This works well most of the time, except for when it breaks, at which >> point I need to resync the two servers, which usually takes days. >> >> I would like to set up something similar using linux. I don't have the >> budget for a SAN/NAS, and even having a third server as storage would >> probably not be worth it, although we can possibly go with this. The >> problem, is that it would be a single point of failure. >> >> Is there some service/filesystem in Linux that allows for the automatic >> replication of files to make a fault tolerant environment possible with >> only 2 servers? Basically whenever there is an update of a file on a >> certain file system (certain folder), the file gets synced over to >> another system. >> >> Russ >> >> >> _______________________________________________ >> CentOS mailing list >> CentOS at centos.org >> http://lists.centos.org/mailman/listinfo/centos >> >> > > DRBD and Heartbeat seem pretty solid together for cheap affective high > availability. We've been using them for our production FTP servers > which handle hundreds of thousands transactions a day both > uploading/downloading. We fail over between the two every 6 months and > haven't had any problems on CentOS 4.3, they've actually been up for > several hundred days now. There is actually a yumgroup named > drbd-heartbeat in the CentOS extras repository but I don't see that it > is available in CentOS 5.0. Does anyone know if these packages will be > available in any of the CentOS 5.0 yum repositories? > > _______________________________________________ > Looks interesting. I will have to try them out once they're in the stable repo. Looks as of DRBD-8.0.0, you can use it together with GFS and run both nodes as primary. Would heartbeat still be needed? Can heartbeat work with VM boxes? Russ