Hi Mike, I took a peak at the diagram. Does the blue cylinder represent an Ethernet switch? You may want to add another switch if it's a full redundant mesh topology youre after. Thanks, Jacob > -----Original Message----- > From: linux-cluster-bounces@xxxxxxxxxx > [mailto:linux-cluster-bounces@xxxxxxxxxx] On Behalf Of > Michael O'Sullivan > Sent: Monday, May 19, 2008 4:15 PM > To: linux-cluster@xxxxxxxxxx > Subject: Re: GFS, iSCSI, multipaths and RAID > > Thanks for your response Wendy. Please see a diagram of the > system at http://www.ndsg.net.nz/ndsg_cluster.jpg/view (or > http://www.ndsg.net.nz/ndsg_cluster.jpg/image_view_fullscreen > for the fullscreen view) that (I hope) explains the setup. We > are not using FC as we are building the SAN with commodity > components (the total cost of the system was less than NZ > $9000). The SAN is designed to hold files for staff and > students in our department, I'm not sure exactly what > applications will use the GFS. We are using iscsi-target > software although we may upgrade to using firmware in the > future. We have used CLVM on top of software RAID, I agree > there are many levels to this system, but I couldn't find the > necessary is hardware/software to implement this in a simpler > way. I am hoping the list may be helpful here. > > What I wanted to do was the following: > > Build a SAN from commodity hardware that has no single point > of failure and acts like a single file system. The ethernet > fabric provide two paths from each server to each storage > device (hence two NICs on all the boxes). Each device > contains a single logical disk (striped here across two disks > for better performance, there is along story behind why we > have two disks in each box). These devices (2+) are presented > using iSCSI to 2 (or more) servers, but are put together in a > RAID-5 configuration so a single failure of a device will not > interrupt access to the data. > > I used iSCSI as we use ethernet for cost reasons. I used > mdadm for multipath as I could not find another way to get > the servers to see two iSCSI portals as a single device. I > then used mdadm and raided the two iSCSI disks together to > get the RAID-5 configuration I wanted. Finally I had to > create a logical volume for the GFS system so that servers > could properly access the network RAID array. I am more than > happy to change this to make it more effective as long as: > > 1) It doesn't cost very much; > 2) The no single point of failure property is maintained; > 3) The servers see the SAN as a single entity (that way > devices can be added and removed with a minimum of fuss). > > Thanks again for any help/advice/suggestions. I am very new > to implementing storage networks, so any help is great. > > Regards, Mike > > -- > Linux-cluster mailing list > Linux-cluster@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/linux-cluster > -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
