ISCSI+mdadm+reiserfs+NFS disk storage

From ISPWiki

Introduction

iSCSI allows to connect all removed physical disks to one machine; RAID array is created there and is formatted into ReiserFS (in this case FS allows to enlarge the partition without demounting), file system is distributed to other machines via NFS.

Advantages of this storage:

1. Low latency
2. Full-scale support of disk quotas
3. Cheap
4. Scalability up to 20 servers. If a partition on one machine is 500 Gb, the storage will be 20 * 500GB = 10TB

Drawbacks :

1. If you use RAID5, only one node crash is supported
2. NFSv4 instability.
3. If the "main node" crashes, you should manually enable iSCSI-disk, RAID and NFS-server on the other machine.
4. Performance bottleneck is the "main" node, that has to address to remote iSCSI-partitions over the network, and create a file system via NFS.

Installing

1. Connect iSCSI-disks. Read ISCSI for more details.
2. Create the RAID-array. See mdadm.
3. Format using ReiserFS. See reiserfs.
4. Customize NFS.