FAQ

• Customers are not asking for iSCSI. How can I sell it?

It may be true as iSCSI as still relatively new in the mind of the end user. Customers may not be asking specifically for iSCSI, but they more than likely have storage problems that could be solved by iSCSI.

If they are outgrowing their current storage capacity - iSCSI can solve this problem.

If they do not have an infinite storage budget - iSCSI can solve this problem.

If they do not perform adequate backups of their critical data because tape is too expensive and difficult to manage - iSCSI can solve this problem.

If they want storage that is flexible, scalable, secure, and fits within their budget - iSCSI can solve this problem.

Rather than promote iSCSI as a technology, promote a storage solution based on iSCSI, and when customers see how simple and economical a solution based on iSCSI is, it will make closing the sale much easier.

• Isn't Fibre Channel better than iSCSI?

When it comes to comparing iSCSI with Fibre Channel, it is not necessarily an either/or situation. Fibre Channel will still have its place in higher end enterprise-level environments. For most SMBs, FC SANs are not even considered due to their cost and complexity, so iSCSI allows them to take advantage of the benefits of a SAN at a price they can afford. Even in enterprise environments, iSCSI will be used for secondary applications such as near-line storage and disk-based backup.

• Is iSCSI better than NAS?

Networked Attached Storage (NAS) and Storage Area Networks (SAN) are used to provide storage in a networked environment. Beyond that, SAN and NAS are used for different purposes. NAS storage is file-based and SAN storage provides direct access to data blocks. File-based storage can translate files into different file systems and is used primarily when there are clients with different operating systems (e.g., Windows and Linux) that need access to the same files.

Because of the overhead of performing the file translation, NAS performance is slower than iSCSI. Therefore, iSCSI is used where higher performance is needed. Because iSCSI is block-based, meaning that it only "sees" 1's and 0's, it does not have the file translation overhead that NAS does. Furthermore, some applications, such as certain database applications, require storage to be block-based and therefore NAS is not a viable option. Since iSCSI storage is generally managed by a server, there is also more control over the storage since it is better integrated with the server's operating system.

• Are IP-SANs secure?

Wasabi Storage Builder for IP-SAN features several mechanisms to ensure that data is secure and protected:

RAID (Redundant Array of Inexpensive Disks) offers data protection in case of a hard drive failure.

LUN masking allows system administrators to assign specific iSCSI targets to iSCSI initiators, and to ensure that an iSCSI initiator cannot see targets to which it is not allowed access.

The Challenge Handshake Authentication Protocol (CHAP) is a user name/password mechanism whereby the iSCSI initiator must supply a valid user name and password in order to login to and establish communication with the iSCSI target. If either the user name or password is incorrect, then access to the iSCSI target is denied.

• Isn't Fibre Channel performance faster?

Fibre Channel bandwidth is higher than iSCSI. Fibre Channel bandwidth is 4 Gigabits per second (Gb/s), or about 400 Megabytes per second (MB/s) as compared to 1 Gb/s, or 100 MB/s for iSCSI. However, Storage Builder for IP-SAN supports Multiple Connections per Session (MC/s), which allows multiple Ethernet ports to be used together to provide higher bandwidth. It also provides failover should one of the data paths fail. Furthermore, 10Gb Ethernet, which delivers 1000 MB/s bandwidth, is coming on the scene.

However, theoretical bandwidth is only one factor to consider when talking about performance. Using garden hoses as an analogy, suppose a half inch diameter hose typically can handle 9 Gallons Per Minute (GPM) of water. In this case, the GPM can also be looked at as the bandwidth of the hose. Now suppose that a three quarter inch diameter hose can handle 17 GPM. The three quarter inch diameter hose seems as if it would be better because it has a higher GPM rating than the half inch diameter hose. However, if the water main were only able to supply water at 8 GPM, the higher GPM rating of the three quarter inch diameter hose has no benefit - the end result will still be that water is moving through either hose at 8 GPM.

Similarly, the available bandwidth of an interface does not necessarily mean that performance will be higher through that interface. For example, database applications perform largely random data operations. Random data transfers are limited by the performance of the hard disks, which are the slowest link in the data transfer chain because of the hard disk mechanism. Random data transfers from hard disks will not come close to reaching the maximum bandwidth of iSCSI, much less Fibre Channel. Therefore, it is best to determine the data transfer rate needs of the specific application(s) and use that as a factor in choosing the proper storage platform.

• Isn't iSCSI too immature to be deployed?

iSCSI has been in development for many years and combines two very mature technologies - Ethernet and SCSI.

iSCSI has the backing of every key industry player.

IP-SANs are deployed and being used now. In a recent InfoStor survey1, 17% of respondents indicated that they had already implemented IP-SAN storage, and 20% indicated that they planned to implement IP-SAN storage in the next 12 to 24 months.

In the same survey users reported that by deploying iSCSI they realized a reduction in capital expenditures and an increased rate of server connectivity.

With security features such as CHAP and LUN masking, iSCSI is secure and robust.