Transcript Storage Networking

Storage Networking
Storage Trends
• Storage growth
• Need for storage flexibility
• Simplify and automate management
• Continuous availability is required
Storage considerations
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Capacity
Performance
Scalability
Availability and Reliability
Backup and recovery requirements
Support/staff needs
Budget
RAID
• Consolidate multiple physical disks into a
logical grouping
• Designed for fault tolerance and
performance improvement
• Can be implemented in H/W or S/W
• Several RAID levels exist
Hardware RAID
• Volume Management performed by RAID
controller
• Parity computation performed by the RAID
controller – decreases server overhead
• Dedicated cache memory improves server
performance
Software RAID
• Performed by the server O/S
• Parity computation performed by the
server – increased overhead
• RAID performance depends on the server
performance and CPU load
• For simple environments with lower
performance and availability requirements
Simple levels of RAID
• RAID 0 – Striping
• RAID 1 – Mirrored Volumes
• RAID 2 – Bit-level striping with parity distributed
to one or more disks
• RAID 3 – Byte-level striping with dedicated parity
disk
• RAID 4 – Block-level striping with dedicated
parity disk
• RAID 5 – Block-level striping with distributed
parity
• RAID 6 – Block-level striping with distributed
double parity
Nested RAID
• RAID 0+1: striped sets in a mirrored set
• RAID 10 (or RAID 1+0): mirrored sets in a
striped set
• RAID 5+1: mirrored striped set with distributed
parity (also known as RAID 53)
• RAID 5+0: striped set of RAID-5 sets
Block-level vs File-level access
• File systems 2 views:
1. Data representation to users/applications (hierarchical
view)
2. Storage organization (data structure)
• Block-level access: write/read blocks;
master/slave relationship
• File-level access: using file names; client/server
relationship
DAS
Block-level access
File system is on the server
SCSI protocol
DAS
NAS
File-level access to the outside; block-level to the storage subsystem
File system is on the NAS device
Clients
IP
Network
File Protocol: SMB/CIFS, NFS, etc.
Servers
NAS
SAN
Block-level access
File system is on the server
Storage Area
Network
SCSI over Fibre Channel
Servers
SAN
SAN
• Traditional SANs used Fibre Channel
protocol and storage technology to
connect SAN at gigabit speeds
• SCSI commands transmitted over FCP
• Expensive
• Requires dedicated network
equipment/architecture
IP Storage
• As an alternative, existing IP infrastructure
can be used
• FCIP, iFC protocols allow Fibre Channel
devices to be connected over IP networks
• iSCSI allows SCSI commands to be
encapsulated to be transferred through an
IP network
iSCSI
• Allows SAN utilize TCP/IP for block-level
data transfer
• Transport for SCSI commands
• Existing networks (routers/switches) can
be utilized – no need for special
equipment
• With current network technologies
supporting gigabit speeds, comparable to
FC in speed
NAS-SAN Integration
Distributed File Systems
• SMB/CIFS; Samba (Windows-based
systems)
• NFS (Unix-based)
• AFS (Unix)
• AFP (MAC)
• NCP (Netware)