Storage Area Network (SAN)

This is simple jot down of things related to Storage Area Network, some specific to HP's EVA 4400.

Components:

EVA – Enterprise Virtual Array
LUN – Logical Unit Number
HSV Controllers – Hierarchial Storage Virtualization Controllers (like VCS & XCS)
LS – Loop Switches
DAE – Disk Array Enclosures (Chassis)
DDE – Disk Drive Enclosures
EPB – Enhanced Port Bypass mode
PDU – Power Distribution Unit
PDM – Power Distribution Models
EAB – Enclosure Address Bus
EMU – Environmental Monitoring Unit
SMS – Storage Management Server
SSSU – Storage System Scripting Utility
EVA Perf – EVA Perfromance Monitoring
42U Rack – is a usual Rack with length of 42 RU. One RU (Rack Unit) or “U-Space” is unit for measuring length of a Server Rack. 1 U = 1.75inches (4.45 cm)

iLO – integrated Lights Out.
Controller contains – Control cache, Read cache, Write cache, Mirror cache

Softwares:

CA EVA – Continuous Access Enterprise Virtual Array (remote replication)
BC – Business Copy (local replication)
RSM – Replication Solution Manager (has GUI to manage CA, BC & features)
VCS – Virtual Controller Software
XCS – Xtensible Controller Software
Code Load – Controller Firmware

Concepts:

Has a pair of HSV Controllers to maintain redundancy at Controller level
Minimum of 8 physical disks are required for creating LUNs (constitutes one Disk Group)
SAN is called of configuration nCmD – n controllers, m Disks. eg. 2C4D = A SAN of 2 Controllers & 4 Disks
1 EMU for each DAE
SNS gives WWN to hosts
Snapshot – point-in-time backup, not continuous I/O. It is always delta data.
Snapclone – Continuous I/O. So, overhead. But is a exact replica. Can be presented as Vdisk.
Mirrorclone – It is at Container level. HP is getting rid of it.
Container – Space has to be specified while creating. This is not used for categorization
Folder – Space need not be specified while creating. This is used for categorization
Data replication is done at Container-level or Vdisk level.
For Mirrorclone, Container is a mandatory. But this concept is slowly going away from market.
Snapclone is a better solution.
EVA Backup is not possible with Command View EVA. Need to use SSSU.
Max LUN size is 2TB, min is 1GB.
Failover – Switches from A to B controller.
Failback – Switches back from B to A once A is alive again.

Options in LUN configuration:

Write Back – Acknowledges after writing to Controller Cache
Write Through – Acknowledges only after writing to hard disk
LUN Mapping – Visible, presented to Host
LUN Masking – Hidden, not presented to Host


Facts:

Battery life – 4 yrs expectancy
Customer cannot Code Load. It has to be with HP's support only.

Features:

One can install OS on one of the LUNs & boot all servers from SAN
Applications can be installed on SAN and servers can start applications from SAN

FC Switch:

Topologies: FC – AL (Arbitrated Loop), FC – SW, FC – P2P
Port types: N_port – on the host
F_port – on the FC Switch
E_port – port for linking to FC-Switches
EX_port – on the FC-Router
U_port – Universal Port


HBA – Host Bus Adapters
WWN – World Wide Network
WWNN – World Wide Node Number (This is the FC Switch number)
WWPN – World Wide Port Number (Port numbers on the FC Switch)

FC – Fibre Channel
FCP – Fibre Channel Protocol
FCIP – Fibre Channel Over IP
iFCP – internet Fibre Channel Protocol

Misc:

MPR – Multi-Protocol Router

IB – InfiniBand (faster speeds than FC)