Latest trends and technologies Latest trends and technologies in Storage Networkingin Storage Networking

By: Gururaja Nittur

Advisor: Dr. Chung E Wang Dr. Chung E WangSecond Reader: Dr. Du Zhang Dr. Du Zhang

Scope of the Project

Study the new technologies in the storage networking arena– Fibre channel protocol

– NAS, SAN and iSCSI

– Storage Virtualization

– High Availability

Demonstrate high availability by writing a DMP(Dynamic Multi Pathing) driver for Solaris

What is Storage Networking?

“The practice of creating, installing, administering, or using networks whose primary purpose is the transfer of data between computer systems and storage elements and among storage elements”

Why Storage Networks?

“The total amount of data being stored doubles every year. Also, more than 90% of companies today would fail to survive a catastrophic data loss. Businesses face a mission-critical need to protect, access, and manage their ever-growing volume of storage assets”

Explosive growth of business data Internet and MultimediaHigh AvailabilityManagement complexity

Why Storage Networks? (Contd..)

Fibre Channel (FC)

A serial, high-speed data transfer technology Open standard, defined by ANSI and OSI Data rate upto 100 MB/sec. (200 MB/sec. full-

duplex) Supports most important higher protocols like

IP, ATM, SCSI etc. Does not have its own command set, but

facilitates data transfers between individual FC devices.

Parallel Transmission

Set of data signals are sent simultaneously through 8, 16 or even more wires.

Problems with parallel transmission– data sent simultaneously over all the wires have to be

received simultaneously as well– Total time = t+dt

• ‘t’ - time taken for the signals to reach receiver• ‘dt’ – additional delay due to hardware inconsistencies• ‘dt’ increases with cable length causing lesser frequency

Example - SCSI• Bus length limitations• Max bus speed is limited (~40 MB/sec in Ultra SCSI)• Limited device count

Serial Transmission

Serial transmission uses single cable– All signals are delayed the same and arrive at

the receiver in the same order in which they were sent.

– Higher bus length

Examples– SSA (Serial Storage Architecture by IBM)– Fibre Channel

Current Technology

DAS using SCSI

Emerging Technologies

Network Attached Storage (NAS)Storage Area Networks (SAN)Storage over IP (iSCSI)

Network Attached Storage

Network Attached Storage

Storage device will have a built-in network interface

NAS unit can be plugged directly into the network to allow quick and easy access

Standard network protocols such as CIFS and NFS can be used to share data

Network Attached Storage

NAS engine is usually SCSI for low-end systems for cost reasons and Fibre Channel for the enterprise systems

NAS is easy to install and relatively easy to maintain

Network is used exclusively for data transfer causing additional overhead

Backup using LAN is really a overhead

Storage Area Networks

Storage Area Networks

As much as 60% of the traffic on a std corporate network is made up of housekeeping actions like Backup

Storage Area Network has been fuelled significantly by the desire to get this housekeeping off the network

Primary interface for SAN infrastructure is Fibre Channel

Storage Area Networks

SAN provides excellent performance and easier management

SAN implementations are expensive due to hardware costs

Better resource sharing could make up for the initial investment

SAN is very flexible in that more storage and servers can be added easily

iSCSI

Motivation – GB Ethernet

iSCSI is a draft standard protocol to encapsulate SCSI commands into TCP/IP packets

Can be used to build IP based SANs

Storage Virtualization

The research firm Gartner Group estimated that 80% of the storage costs is used up for managing the installed storage

Switch and array management becomes very difficult with increased storage hardware

Virtualization provides a logical view and eases management.

Examples – Veritas Volume Manager, IBM Tivoli etc.

Future of network storage

SAN islands connected by IP networks Network Unified Storage (NUS)

– NAS + SAN on GB Ethernet networks

High Availability

HostHost

Disk

Single Point Failure

HostHost

Disk

Multi Pathing

Dynamic Multi Pathing

Increased disk availabilityLoad balancingIdentifies disks uniquely from different

hosts

Dynamic Multi Pathing

HostHost

Disk

..

/dev/rdsk entries/dev/rdsk entriesc1t1d0c2t1d0

….cnt1d0

HostHost

/dev/rdsk entries/dev/rdsk entriesc1t1d0c2t1d0

….cnt1d0

Implementation Details

Scan the disks listed in /dev/rdsk If no UUID is present, generate a unique UUID

and stamp it in the disk’s private regionAdd this device to a hash table hashed on UUIDLoad this table to the kernel and write the ioctls to

update this infoUse an algorithm (Currently round robin) to

efficiently load balance the I/O requests. If a path is bad for more than five I/O attempts,

mark it bad and do not use it for path selection.

Implementation Details

User code– Read /dev/rdsk folder and generate a hashed list of

available disks– Load this list to kernel. Also provide APIs to push newly

added/removed disks.Kernel code

– Filter driver to choose the best path– ioctls to do the following

• LOAD_DISKS• NEW_DISK• MODIFY_DISK• GET_DISK_HANDLE …

Questions??Questions??