latest trends and technologies in storage networking by: gururaja nittur dr. chung e wang advisor:...
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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??