1. Latest trends and technologies in Storage Networking
By: Kulveer singh

2. 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

3. 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”

4. Why Storage Networks? Explosive growth of business data
“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 Multimedia
High Availability
Management complexity

5. Why Storage Networks? (Contd..)

6. 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.

7. 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

8. Serial Transmission Serial transmission uses single cable Examples
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

9. Current Technology
DAS using SCSI

10. Emerging Technologies
Network Attached Storage (NAS)
Storage Area Networks (SAN)
Storage over IP (iSCSI)

11. Network Attached Storage

12. 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

13. 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

14. Storage Area Networks

15. 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

16. 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

17. 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

18. 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.

19. Future of network storage
SAN islands connected by IP networks
Network Unified Storage (NUS)
NAS + SAN on GB Ethernet networks

20. High Availability Host Single Point Failure Disk Host Multi Pathing

21. Dynamic Multi Pathing Increased disk availability Load balancing
Identifies disks uniquely from different hosts

22. Dynamic Multi Pathing Host .. Disk /dev/rdsk entries c1t1d0 c2t1d0 ….
cnt1d0

23. 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 region
Add this device to a hash table hashed on UUID
Load this table to the kernel and write the ioctls to update this info
Use 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.

24. 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 …

25. Questions??