The document discusses Gosuke Miyashita's goal of building a scalable storage system for his company's web hosting service. He is exploring the use of several open source technologies including cman, CLVM, GFS2, GNBD, DRBD, and DM-MP to create a storage system that provides high availability, flexible I/O distribution, and easy extensibility without expensive hardware. He outlines how each technology works and shows some example configurations, but notes that integrating many components may introduce issues around complexity, overhead, performance, stability and compatibility with non-Red Hat Linux.

1. TLUG Meeting 2008/09/13 Gosuke Miyashita

8. CLVM clvmd distributes metadata among cluster nodes Logical volumes presented to each cluster node Logical volume on shared storage LVM2 Metadata clvmd LVM2 Metadata clvmd LVM2 Metadata clvmd

10. GNBD TCP/IP network GNBD client GNBD client GNBD client GNBD Server Exported block device

12. GFS2 These nodes can access to the GFS2 file system simultaneously GNBD Server GFS2 GNBD client cman GNBD client cman GNBD client cman

14. DRBD Replication Server Block Device Server Block Device

16. DM-MP with SAN storage /dev/sda1 /dev/sdb1 Seen as one device /dev/mapper/mpath0 active/passive or active/active Node HBA1 HBA2 SAN swtich 1 SAN swtich 2 Storage CNTRLR1 CNTRLR2

18. A scalable storage system /dev/VG0/LV0 (CLVM) mount /dev/VG0/LV0 /mnt cman GNBD cman GNBD GNBD Server GFS2 GNBD Server GFS2 Replication (DRBD) /dev/mapper/mpath0 (DM-MP) /dev/gnbd0 /dev/gnbd1 GNBD Server GFS2 GNBD Server GFS2 Replication (DRBD) /dev/mapper/mpath1 (DM-MP) /dev/gnbd2 /dev/gnbd3

19. How to extend /dev/VG0/LV0 (CLVM) mount /dev/VG0/LV0 /mnt cman GNBD cman GNBD GNBD Server GFS2 GNBD Server GFS2 /dev/mapper/mpath0 /dev/gnbd0 /dev/gnbd1 GNBD Server GFS2 GNBD Server GFS2 /dev/mapper/mpath1 /dev/gnbd2 /dev/gnbd3 GNBD Server GFS2 GNBD Server GFS2 /dev/mapper/mpath2 /dev/gnbd4 /dev/gnbd5