StorageTek Hears an Echo

Storage Technology Corp. (StorageTek) (NYSE: STK) is getting ready to roll out EchoView, an iSCSI-based appliance that the company claims can completely eliminate backup windows by automatically mirroring data the instant it's created or changed.

The device uses host-based software agents that send data via iSCSI -- a standard protocol for sending block-level storage over IP -- to the EchoView server, allowing it to restore a given data set from any point in time. EchoView can also then back up the data to tape, offloading this task from application servers.

"It provides continuous data protection, so it eliminates the risk window where data has been created but not backed up," says Bill Chait, senior product marketing manager for EchoView.

The new StorageTek backup appliance represents the confluence of two major trends in the storage networking industry: IP storage and disk-based backup. Less-expensive disk storage and iSCSI are allowing vendors to deliver new and more cost-effective ways to protect data (see Disk Backup 101 and IP SANs: Coming of Age).

The first EchoView family member, the E400, is slated to start shipping next month in limited quantities at a list price of $50,000. The E400 has about 900 Gbytes of raw disk storage, although StorageTek says the unit is able to protect between 200 and 400 Gbytes of data, depending on various factors including how frequently the data is updated and a user's data-retention policy. The E400, which is based on a PC server, provides up to ten Gigabit Ethernet ports and can monitor up to 50 volumes.The appliance provides a level of functionality that fits in between mirroring and snapshot, according to StorageTek. EchoView tracks all writes from protected servers using journaling, a method of keeping track of which blocks have changed in a data set.

Unlike mirroring, EchoView allows users to go back to a specific point in time. "Besides being expensive, mirroring only protects you from hardware failures, not data corruption," says Chait. He adds, however, that EchoView does not provide failover capabilities in the event that the primary storage goes offline, so StorageTek does not recommend that it be used as a primary mirror.

Meanwhile, unlike with snapshots, EchoView agents on the server automatically copy data every time there's a write to disk rather than only at specific points in time. "With snapshot, if you needed to get back to 3:55 p.m. and you've done a snapshot at 4 p.m., you're fine -- but you never know when a failure is going to occur," he says.

The appliance also allows end users to restore files themselves, using the Windows Explorer interface, based on the same access rights that are provide by the volume management software customers are using.

Figure 1: Typical EchoView ConfigurationSource: StorageTek

StorageTek first described EchoView in November 2002 as software that would work in conjunction with its BladeStore ATA-based arrays (see StorageTek Puts Backups on Auto).

The company decided to deliver EchoView in a hardware package, Chait says, to minimize the performance degradation on the servers. For this reason, EchoView will require users to install a QLogic Corp. (Nasdaq: QLGC) iSCSI adapter, which includes a TCP offload engine (TOE), in every server they're protecting. Even at full throttle, the QLogic adapter consumes less than 5 percent of the host CPU, Chait claims.

"We sit on top of the device driver stack, and pass the writes over to the iSCSI TOE," he says.

StorageTek's list price for the QLogic iSCSI HBAs will be $1,700. The company expects to eventually certify other adapters to work with EchoView. ISCSI adapter vendors include Adaptec Inc. (Nasdaq: ADPT), Alacritech Inc., and Intel Corp. (Nasdaq: INTC) (see Adaptec Shipping iSCSI).

The E400 initially will support Windows 2000 and Solaris. Later in the summer, StorageTek plans to release support for AIX, HP-UX, and Linux; Windows Server 2003 is on the roadmap.The only caveats that seem to be in order for EchoView are that it's a first-generation product based on iSCSI -- which is, as yet, an unproven technology in the marketplace.

In the fall, StorageTek expects to release the higher-end EchoView E1000, which will protect 500 Gbytes to 2.5 Tbytes using StorageTek's BladeStore on the back end, and will support Fibre Channel connectivity. Also on the EchoView roadmap is more comprehensive database support to provide consistent point-in-time views of Oracle and Microsoft SQL Server data.

Todd Spangler, US Editor, Byte and Switch