What is iSCSI?

Learn about iSCSI and its benefits

NAS Servers

iSCSI, or internet SCSI, is an IETF standard which maps SCSI blocks into Ethernet packets. Fundamentally, the iSCSI protocol is a method for transporting low latency SCSI blocks across IP networks.

iSCSI also allows you to build storage area networks over IP using something you already know and use everyday: Ethernet. In this way, iSCSI removes the limitations of direct attached storage, including the inability to share storage resources across servers and to expand capacity without shutting down applications.

Benefits of iSCSI SANs

  • High Availability: Multiple paths between servers and storage enable a constant connection, even if some lines go down.
  • Scalability: The switched architecture of SANs enable IT managers to expand storage capacity without shutting down applications.
  • Maximize Storage Resource Investment: SANs allow you to share disk and tape devices across heterogeneous platforms.

iSCSI Diagram

Four Common Problems iSCSI Solves

1. Underutilized Storage

In most IT shops, where Direct Attached Storage (DAS) is common place, the storage is held captive behind servers and is typically only accessible by the server that is attached to it. Studies have shown that the average DAS deployment experiences only 50% utilization of the storage. This means that the limitations placed on storage in a DAS environment requires that IT managers resort to guesswork to estimate storage growth requirements.

The solution to low storage utilization is the deployment of a Storage Area Network (SAN). Studies show that SANs experience 85% storage utilization. The increased storage utilization in SANs is derived from the ability to consolidate storage and create a shared storage resource for all server applications. iSCSI is a protocol that enables the creation of SANs using Ethernet.. iSCSI takes the guess-work out of deploying storage.

2. Shrinking Backup Windows

In the new digital economy storage backup has become an increasingly difficult task. There are only 24 hours in a day and many of those hours are consumed with real-time transactions with the storage. This constant access to storage has reduced the amount of time a server can be off-line to do backups. The solution is to create a dedicated backup system that can take server data to tape or disk with no impact to the LAN and with no server downtime.

iSCSI is the technology that enables IT shops to do server backup with no LAN impact and no server downtime. With iSCSI, data can be backed up over a SAN to a shared storage resource. In addition, because iSCSI is an Ethernet-based storage protocol, it enables backup resources to be geographically dispersed. This enables IT managers to logically, rather than physically, configure storage and to de-couple backup resources from the data center to a safer location.

3. Restricted Storage Growth

Limited budgets have forced IT managers to do more with less. iSCSI SANs help IT managers meet their budgetary constraints by allowing them to add storage when needed without having to significantly increase headcount to manage the storage. In addition, the flexibility to add storage on the fly eliminates the guesswork in deploying storage for anticipated growth and allows IT managers to fully utilize the purchased storage.

iSCSI SANs provide all the same benefits as any storage area network. This means that users can consolidate storage, configure storage logically rather than physically, backup storage with no LAN impact and add storage by simply plugging storage into the existing infrastructure.

4. Distance Limitations

Most storage protocols limit the physical distance between storage and the systems where applications reside. By using the existing Ethernet infrastructure, iSCSI SANs eliminate the distance barrier from the application system to the storage.

Eliminating distance barriers means that remote sites can be more seamlessly linked to the data center. iSCSI SANs enable mission critical applications such as disaster recovery as well as remote backup and restore allowing for business continuance. In addition, iSCSI SANs allow for data centers to be linked to each other and to mirror data across geographically disperse locations.

Frequently Asked Questions about iSCSI

Will IP Storage be as fast as Fibre Channel or faster?
Rated speeds are comparable. So, 1G Fibre Channel (FC) will have throughput equivalent to 1G IP Storage. 2G FC will have throughput faster than 1G IP Storage. We see FC as a viable alternative for companies willing to invest in dual fabrics. Very quickly, IP Storage will show a total cost of ownership better than FC. At 10G, IP Storage will likely be the fabric and technology of choice.
Will IP Storage products be cheaper than Fibre Channel products?
In low performance applications using standard NICs, yes. For higher performance using offload and accelerated HBA's the HBA will cost about the same as FC, but the fabric - Ethernet switches, routers and hubs - will cost less. The total cost of ownership will favor IP Storage significantly.
What is the difference between IP Storage and iSCSI?
IP Storage is a technology that encompasses block storage transfer over an IP network. iSCSI is a protocol standard for encapsulating SCSI in TCP/IP for transfer over an IP network.
Which technology is best to use to implement a SAN this year - IP Storage or Fibre Channel?
The answer here depends on more than a one-year outlook. For companies with larger budgets, and the willingness to learn FC technology, there may be a short term advantage. For companies more concerned with total cost of ownership and leveraging their network infrastructure, IP Storage is the way to go.
Why should I choose Thinkmate IP Storage products?
Thinkmate has the most expertise in IP storage solutions - plus proven quality and value for our dealers and customers. Thinkmate works with the leading component manufacturers to assure our products have the highest quality and workmanship.