Storage Networking Storage Trends Storage growth Need for

Storage Networking

Storage Trends • Storage growth • Need for storage flexibility • Simplify and automate management • Continuous availability is required

Storage considerations • • Capacity Performance Scalability Availability and Reliability Backup and recovery requirements Support/staff needs Budget

File System Functions • Local FS: FAT, FAT 32, NTFS, HFS, etc. • A file system consists of structures for storing and managing data • Maintaining directories (folders) and file names • Tracking where each file is physically stored on the disk

File system

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

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

RAID 0

RAID 5

RAID 1

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

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, i. FC protocols allow Fibre Channel devices to be connected over IP networks • i. SCSI allows SCSI commands to be encapsulated to be transferred through an IP network

i. SCSI • 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)