Emmanuel Noobadmin wrote, On 08/04/2010 11:33 AM: > Easier because instead of running gluster raid 0 on top of DRBD raid > 1, we can take out the DRBD layer and just use gluster to achieve the > equivalent by distribute on replicate. > > More importantly there is the issue of cost, DRBD needs a pair of > server per node for active-active. However, gluster allows me to get > RAID "0.67" redundancy by "round robin" replicate. > I missed this. > i.e. If every storage node has 2 mdraid 1 block devices md0 and md1, I > can mirror Server1 md0 to Server2 md1, Server2 md0 to Server3 md1 and > so forth. Theoretically capable of surviving up to 50% node failure if > no two adjacent node fails together. This for the cost of N+1 as > compared to DRBD's Nx2 cost. DRBD cost would still be N+1, not Nx2, if setup similarly, I think. If Gluster is doing the mirror of "Server1 md0 to Server2..." by itself, then yes adding DRBD to it would be a bit overkill, as I would be having DRBD setup to do something similar. -- Todd Denniston Crane Division, Naval Surface Warfare Center (NSWC Crane) Harnessing the Power of Technology for the Warfighter