Internet SCSI
Internet Protocol (IP) is the most widely used standard anywhere. The technology is well understood. It’s easy to implement and is affordable. Most corporate data traffic uses a common IP network…except for storage data. Access to high performance storage data traditionally requires directattached devices or a Fibre Channel (FC) storage network. Internet SCSI (iSCSI) transports traditional high performance “block-based” storage data over a common IP network. Which means - it can be used in
remote mirroring, remote backup and similar applications since an IP
network has no distance limitations.
As iSCSI begins to achieve widespread market adoption, barriers to implementing and managing networked storage can be removed by incorporating IP networking into a storage network.
SCSI
Most servers access storage devices through the Small Computer Systems Interface (SCSI) standard, moving “blocks” of data among computer systems. But its limitations became clear as demand for storage capacity grew.
SCSI’s built-in limitations on distance, number of devices supported and exclusive ownership of a server to its respective SCSI storage device prohibited the creation and sharing of a common pool of storage.
Fibre Channel/SAN
Creating a shared storage environment is best done with networked storage. Fibre Channel (FC) is the basis for building a Storage Area Network (SAN)
and popular because it offers:
• high performance,
• support for longer distances than SCSI,
• ability to transport block-level data, and
• capability to scale to large network configurations.
Although no longer proprietary, FC based storage networks do have some
baggage:
• complexity,
• cost
• difficult to install and manage.
NAS
Another method of networking storage is to attach the storage device directly to an existing Ethernet network in a Network Attached Storage (NAS) configuration. NAS is typically a simpler and lower cost than a SAN.
It leverages the benefits of using an IP network, such as support for significantly longer distances. However, NAS is slower than FC SAN. Data transport is managed at file level – not the block level. This significantly slows data access in transactional or database applications. Issues of
scalability, centralization and management of a single pool of storage increase as the number of NAS systems deployed in a site increases.
A new solution was needed that offered the low cost and ease of deployment of NAS systems and the functionality of SAN. That’s where iSCSI plays.
How iSCSI Works
Internet SCSI (iSCSI) enables server host applications to perform traditional “block-level” transactions over a common IP network. It’s built on two of the most commonly understood protocols: SCSI and Ethernet, the dominant standards for storage and networking.
Using an ordinary IP network, iSCSI transports block-level data between an iSCSI initiator
on a server and an iSCSI target on a storage device.
The iSCSI protocol encapsulates SCSI commands and assembles the data in packets for the TCP/IP layer. Packets are sent over the network using a point-to-point connection. Upon arrival, the protocol translates data back to SCSI. Security is provided through iSCSI authentication and virtual private
networks (VPNs), as needed.
When an iSCSI initiator connects to an iSCSI target, the operating system sees the storage as a local SCSI device that can be formatted as usual. The process is transparent to applications, file systems, and operating systems. By consolidating storage with an iSCSI SAN, different platforms can share the
same storage, greatly improving utilization and efficiency. Multi-protocol switches let iSCSI and Fibre
Channel SANs co-exist
To access iSCSI storage, a server needs an iSCSI initiator connected to a network. An initiator can be an iSCSI driver with a standard network card, or a card with a TCP offload engine (TOE) to reduce CPU utilization. HBAs are available that offload both TCP and
iSCSI.
On the target side, storage devices also implement the iSCSI protocol stack.
The primary benefits of iSCSI leveraging IP are clear:
• no distance limitation
• lower cost
• well understood technology
• easy to administer and manage
• high availability (multiple connection paths)
• better performance than NAS (block level access instead of file level)
• maximum utilization of resources (share disk and tape devices across
a heterogeneous environment).
FC SANs may be faster and have greater adoption and more robust management tools than iSCSI offers today. But, IP SANs are simpler and more affordable to implement than traditional FC SANs. And, with the 10 GbE, iSCSI on the horizon, IP SANs will benefit from the faster transfer rates.
But iSCSI need not replace FC to fit in the enterprise.
Benefits of iSCSI
• Makes consolidated storage possible for a wide range of businesses.
• Enables cost-effective, scalable, secure, and highly-available SANs.
• Leverages existing management skills and network infrastructure.
• Delivers performance comparable to Fibre Channel.
• Provides interoperability using industry standards.
• Implemented by the top system, storage, and network providers.
With iSCSI, businesses can get a handle on storage administration expenses
without retrofitting their existing network infrastructure or investing in
hardware that quickly becomes obsolete. Enabling low cost, interoperable,
and high performance SANs, iSCSI is about to revolutionize the world of
networked storage.
Internet Protocol (IP) is the most widely used standard anywhere. The technology is well understood. It’s easy to implement and is affordable. Most corporate data traffic uses a common IP network…except for storage data. Access to high performance storage data traditionally requires directattached devices or a Fibre Channel (FC) storage network. Internet SCSI (iSCSI) transports traditional high performance “block-based” storage data over a common IP network. Which means - it can be used in
remote mirroring, remote backup and similar applications since an IP
network has no distance limitations.
As iSCSI begins to achieve widespread market adoption, barriers to implementing and managing networked storage can be removed by incorporating IP networking into a storage network.
SCSI
Most servers access storage devices through the Small Computer Systems Interface (SCSI) standard, moving “blocks” of data among computer systems. But its limitations became clear as demand for storage capacity grew.
SCSI’s built-in limitations on distance, number of devices supported and exclusive ownership of a server to its respective SCSI storage device prohibited the creation and sharing of a common pool of storage.
Fibre Channel/SAN
Creating a shared storage environment is best done with networked storage. Fibre Channel (FC) is the basis for building a Storage Area Network (SAN)
and popular because it offers:
• high performance,
• support for longer distances than SCSI,
• ability to transport block-level data, and
• capability to scale to large network configurations.
Although no longer proprietary, FC based storage networks do have some
baggage:
• complexity,
• cost
• difficult to install and manage.
NAS
Another method of networking storage is to attach the storage device directly to an existing Ethernet network in a Network Attached Storage (NAS) configuration. NAS is typically a simpler and lower cost than a SAN.
It leverages the benefits of using an IP network, such as support for significantly longer distances. However, NAS is slower than FC SAN. Data transport is managed at file level – not the block level. This significantly slows data access in transactional or database applications. Issues of
scalability, centralization and management of a single pool of storage increase as the number of NAS systems deployed in a site increases.
A new solution was needed that offered the low cost and ease of deployment of NAS systems and the functionality of SAN. That’s where iSCSI plays.
How iSCSI Works
Internet SCSI (iSCSI) enables server host applications to perform traditional “block-level” transactions over a common IP network. It’s built on two of the most commonly understood protocols: SCSI and Ethernet, the dominant standards for storage and networking.
Using an ordinary IP network, iSCSI transports block-level data between an iSCSI initiator
on a server and an iSCSI target on a storage device.
The iSCSI protocol encapsulates SCSI commands and assembles the data in packets for the TCP/IP layer. Packets are sent over the network using a point-to-point connection. Upon arrival, the protocol translates data back to SCSI. Security is provided through iSCSI authentication and virtual private
networks (VPNs), as needed.
When an iSCSI initiator connects to an iSCSI target, the operating system sees the storage as a local SCSI device that can be formatted as usual. The process is transparent to applications, file systems, and operating systems. By consolidating storage with an iSCSI SAN, different platforms can share the
same storage, greatly improving utilization and efficiency. Multi-protocol switches let iSCSI and Fibre
Channel SANs co-exist
To access iSCSI storage, a server needs an iSCSI initiator connected to a network. An initiator can be an iSCSI driver with a standard network card, or a card with a TCP offload engine (TOE) to reduce CPU utilization. HBAs are available that offload both TCP and
iSCSI.
On the target side, storage devices also implement the iSCSI protocol stack.
iSCSI Storage Setup
Unified Storage (NAS + IP SAN)
iSCSI Storage Setup - Server & Client
Comparision
The primary benefits of iSCSI leveraging IP are clear:
• no distance limitation
• lower cost
• well understood technology
• easy to administer and manage
• high availability (multiple connection paths)
• better performance than NAS (block level access instead of file level)
• maximum utilization of resources (share disk and tape devices across
a heterogeneous environment).
FC SANs may be faster and have greater adoption and more robust management tools than iSCSI offers today. But, IP SANs are simpler and more affordable to implement than traditional FC SANs. And, with the 10 GbE, iSCSI on the horizon, IP SANs will benefit from the faster transfer rates.
But iSCSI need not replace FC to fit in the enterprise.
Benefits of iSCSI
• Makes consolidated storage possible for a wide range of businesses.
• Enables cost-effective, scalable, secure, and highly-available SANs.
• Leverages existing management skills and network infrastructure.
• Delivers performance comparable to Fibre Channel.
• Provides interoperability using industry standards.
• Implemented by the top system, storage, and network providers.
With iSCSI, businesses can get a handle on storage administration expenses
without retrofitting their existing network infrastructure or investing in
hardware that quickly becomes obsolete. Enabling low cost, interoperable,
and high performance SANs, iSCSI is about to revolutionize the world of
networked storage.
No comments:
Post a Comment