Tape library manufacturer Spectra Logic recently conducted a benchmark test that the company claims shows iSCSI backup performance is essentially equal to Fibre Channel in terms of performance for Microsoft Exchange database backups.
“These results validate expectations that iSCSI presents an important new opportunity for IT organizations to implement storage consolidation at a fraction of the cost of Fibre Channel,” the company says.
Spectra Logic’s engineers simulated a realistic customer environment by performing a hot backup operation of a Microsoft Exchange 2000 database. The database was first backed up over a Gigabit Ethernet network using iSCSI and then repeated over a 1 Gigabit Fibre Channel SAN.
The results showed surprisingly little difference.
At 33 MB/sec for iSCSI and only 35 MB/sec for Fibre Channel, there was effectively no difference in performance.
“This data confirms that in a Microsoft Exchange environment, it is the software and server hardware configuration that determines backup performance, not the storage network,” says Spectra Logic. “Given equal performance, with an 88% cost advantage, iSCSI should quickly become the backup consolidation network of choice for Microsoft Exchange environments.”
“If the e-mail server cannot stream data fast enough to fill a Fibre Channel pipe, why pay for one?” states Sharon Isaacson, senior product manager for Spectra Logic. “With much lower acquisition and management costs, iSCSI-based storage networking performance is a much better match to the performance capabilities of the typical Exchange application environment.”
iSCSI Competes Where Cost Counts, Analyst Says
Enterprise Management Associates senior analyst Mike Karp agrees that iSCSI backups “show immediate cost benefits, all things being equal, because they run over existing infrastructure, and Fibre Channel is not cheap to install.”
Karp has two caveats for the Spectra Logic benchmark test, however.
First, the test assumes 1 Gb Fibre Channel connectivity, but most Fibre Channel providers are now upgrading to 2 Gb, Karp contends, which should double the throughput for Fibre-based backups.
“This may seem like a killer point, but it isn’t, as this added speed for Fibre will only be of value in situations where the apps can extract enough data from the disks so that they take advantage of the extra bandwidth,” explains Karp. “Many existing environments will find iSCSI-based backups to be more than sufficient in terms of performance, and extremely attractive because they add no additional infrastructure expense.”
Karp’s second caveat is that if the existing data network is used for backups, there will be some impact on other applications using the network.
But in situations where money is an issue, iSCSI has now become a player.
“The combination of new serial ATA (SATA) drives plugged into iSCSI storage systems, plus this new iSCSI-based backup solution, means that iSCSI technology is now in a position to give Fibre Channel-based storage environments a good run for the money in cost-sensitive situations,” confirms Karp.
Spectra Logic offers libraries with integrated support for both iSCSI and Fibre Channel storage networks, and claims to offer the only product line capable of supporting both protocols simultaneously and scaling them independently in the same library. The company began shipping iSCSI tape libraries last month.
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