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IP storage

IP rising

IP storage is not new to India Inc. NAS-and IP-based technology—has been widely deployed. That said, advances in this field have taken IP storage to the big league where Fibre Channel once ruled. IP is set to take enterprise storage by storm—especially in the SMB segment. by Anil Patrick R

Information must be available on the fly with reduced costs. A cliché, but a truth that CIOs cannot ignore. This is where IP storage is quietly stepping in, causing disquiet to its more popular fibre channel-based cousins.

IP-based storage has attained increased prominence at the enterprise level because of the cost factor. It helps in total consolidation of storage resources at a lower cost and centralises the storage architecture
Ajaz Munsiff, Regional Practice Leader, EMC Corporation

The developments in IP-based storage technology are of extreme relevance to organisations worldwide, and increasingly so to the Indian enterprise. This is because in the last few years, many Indian organisations realised the need to shift from traditional DAS-based storage solutions to higher capability options such as SANs. However, Fibre Channel (FC) SANs tend to elude these aspirants because of high costs and issues such as complexity and interoperability.

IP-based storage emerges as a strong contender with its strengths on the cost, capacity, scalability and manageability fronts. "Proponents of IP-based storage claim that it offers a number of benefits over the FC alternative, and will promote the widespread adoption of SANs that was predicted when they were first introduced," says Ramanujam Komanduri, General Manager, Storage, Sun Microsystems India.

This rise has been mainly due to advances in Ethernet and hard disk technology that have helped IP storage to get maximum results from TCP/IP networks and to gain a significant cost benefit. According to Ajaz Munsiff, Regional Practice Leader, EMC Corporation, "IP-based storage has attained increased prominence at the enterprise level because of the cost factor. It helps in total consolidation of storage resources at a lower cost and centralises the storage architecture."

Before examining the latest in IP storage, we need to retrace the path travelled by IP-based storage technology to the present.

First light

The first real enterprise application of IP storage was the Network Attached Storage (NAS) device. This provided enterprises with network storage that was cost-effective and easy to implement/manage.

NAS was first developed close to late 1980s by the now defunct Auspex Systems. The Auspex NAS was based on earlier file servers (IBM, Novell and Microsoft). However, it was when Network Appliance bought over the patents from Auspex and introduced their range of filers that NAS really hit the mainstream.

The main success of NAS has been that it is a low cost and convenient way to organise, manage and access data stored on file systems such as the Network File System (NFS) or Common Internet File System (CIFS). Best of all, the only tasks required to operate a NAS are assigning an IP to the device, tweaking the necessary settings and putting it on a TCP/IP network. This has resulted in NAS vendors making a large profit on the enterprise storage market with the Direct Attached Storage (DAS) market taking a major hit.

However, pure play NAS devices are capable of only file level data transfer, which restricts their usage in applications such as Online Transaction Processing (OLTP) requiring the faster block level data transfer capabilities available only from SANs.

Storage management, consolidation and network utilisation also become issues if there are too many NAS devices across the network. Because NAS devices use the same LAN, network choke-ups can become routine during backups or during peak data traffic.

FC blues

iSCSI host connectivity to FC SANs offers significant cost savings for both medium and large enterprises, and enables new strategies including enterprise-wide tape backup
Tom Clark, Director, Solutions and Technologies, McData Corporation

FC SANs have their limitations as well, mainly on the cost, complexity and interoperability fronts.

First, the entry-level costs of FC SANs are high. When organisations do a TCO/ROI assessment, FC SANs are chosen only for crucial requirements and considering future scalability.

Enterprises might not go in for fibre channel connectivity at all servers, because every fibre or host adapter card can cost thousands of dollars. Most FC SANs are monolithic in nature and future scaling up of SAN storage can be quite expensive. While this might not be a major investment for large enterprises, it is definitely not an affordable proposition for SMBs or enterprises requiring a standby DR site or separate branch office SANs.

Complexity is the next inherent issue with FC SANs. Most FC SANs use proprietary technology requiring training and experience for the storage administrator. As many SAN users have found, acquiring this expertise is not easy. Further, with the prevalent high attrition levels, it can be quite difficult to retain good administrators. Complexity also causes flexibility issues.

FC SAN technology is not exactly known for its interoperability. The proprietary nature is again the culprit. Different FC SAN vendors' products still do not interoperate perfectly. Organisations are, therefore, compelled to stick to the 'one vendor' policy for FC SANs.

Standardisation efforts by industry bodies such as the Storage Networking Industry Association (SNIA) have helped FC SANs interoperate largely on the basic Fibre Channel Protocol (FCP) and fabric levels. However, perfect interoperability (especially for advanced features) is still remote.

Arise, the IP clan

So what's the best thing that has happened so far to IP Storage? Internet SCSI (iSCSI), which, along with a couple of other new technologies, has brought capabilities never before seen to IP storage solutions.

The iSCSI standard was developed by Internet Engineering Task Force (IETF) to transmit SCSI data over a TCP/IP network. It was standardised in February 2003 and has developed as a much hyped/abused standard (depending on which vendor you talked to) to its present strength.

iSCSI is capable of block level data transfer and has evolved as a worthy competitor to FCP. However, the biggest benefit of iSCSI is that it uses TCP/IP networks and can use existing network infrastructure and administrator skill sets to offer low-cost connectivity for consolidation.

"iSCSI host connectivity to FC SANs offers significant cost savings for both medium and large enterprises, and enables new strategies including enterprise-wide tape backup," reveals Tom Clark, Director, Solutions and Technologies, McData Corporation.

Most of the storage solutions available today, including FC SAN switches and NAS devices with iSCSI interfaces, offer iSCSI support. "iSCSI extends SAN benefits to stranded servers and storage. It also provides a cost-effective IP storage infrastructure for entry-level SANs. In the case of NAS devices, it extends NAS consolidation capabilities to include traditional block applications," says Ajaz Munsiff.

The potential of iSCSI is evident from the fact that the list of iSCSI-savvy products includes those from some of the past vocal opponents of iSCSI. After all, no vendor wants to be left behind! Therefore, they have also launched iSCSI-based products or provide iSCSI support in their solutions. iSCSI has also spawned a new generation of cost-effective, yet high-performance storage solutions.

One of the best iSCSI applications is the IP SAN. IP SANs employ iSCSI along with Gigabit Ethernet (GbE) and cheaper high capacity technologies such as Serial ATA (SATA) hard disk drives to obtain innovative high performance IP storage solutions. According to Avijit Basu, Country Manager, HP StorageWorks Division, "iSCSI's ease of use and extensive support from different operating systems enable it to deliver everything that FCP can offer more cost effectively by deploying managed IP SAN infrastructures."

With GbE becoming common in the enterprise, IP SANs have started competing with 1 Gbps FC SANs. To discover more about this innovative SAN development, read the next story 'IP for the SAN'. Apart from iSCSI, other (earlier) developments in IP storage include NAS-SAN gateways to connect NAS devices to SANs.

Timeline: The evolution of iSCSI

1998 - Proof-of-concept (IBM Research).

03/2000 - First draft of iSCSI standard presented at the IETF. Main author is Julian Satran, IBM Haifa Research Lab. Original contributions from IBM and Cisco.

09/2000 - Demo at CERN and Network World+Interop.

06/2001 - GA of IP Storage 200i, first iSCSI appliance in the industry.

07/2001, 11/2001, 02/2002, 07/2002 - iSCSI Interoperability Plugfests.

08/2001 - Boot over iSCSI (iBoot) for Linux.

02/2002 - Boot over iSCSI for Windows.

08/2002 - iSCSI specification passes IP Storage Working Group last call.

Source: http://www.haifa.il.ibm.com/projects/storage/iSCSI/history.html

Going the long route

While iSCSI is charting new paths in corporate LAN, IP has also been active on the SAN-SAN connectivity front. FCIP (Fibre Channel over IP) and iFCP (Internet Fibre Channel Protocol) are two standards that can connect FC SANs using the Internet.

Optic fibre has limited maximum distance of deployment. This makes it essential to find an alternative cost-effective technology if the SANs are further apart. FCIP and iFCP attempt to bridge this gap by transmitting FCP data over the Internet. These technologies can greatly boost the typical enterprise MAN/WAN's potential. "Storage over long distance using iFCP (Internet Fibre Channel Protocol) and FCIP (Fibre Channel over IP) is now widely deployed by large enterprises and is making disaster recovery and remote storage consolidation affordable for medium-size businesses," says Tom Clark.

FCIP-based products are available from Brocade and McData. On the iFCP products front, McData is the only player dabbling with the technology at present. For a detailed overview of FCIP and iFCP, refer to the story 'Save it for the WAN'.

Staying future-proof

Present storage investments must be made considering the IP storage option. In the case of organisations that have already made FC investments, it is advisable to go in for future storage investments with IP compatibility in mind.

Some of the basic features to look for in new storage investments are multi-protocol support, simplified management of multiple switches and fabrics, and integrated multilevel performance analysis. Other desirable features include simplified SAN management, SAN security, VSAN (Virtual SAN) support and compliance with industry standards.

In the industry standard compliance context, new additions to the existing storage infrastructure should preferably have support for iSCSI and FCIP/iFCP. VSAN capability is another useful feature to consider when investing in IP SANs. It is similar to the VLAN (Virtual LAN) capability available in Ethernet switches. The feature helps storage administrators zone the IP SAN into distinct virtually separated SANs.

Anil Patrick R can be reached at anilpatrick@networkmagazineindia.com

 
     
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