Overland, Spectra tap iSCSI for backup and restore

When was the last time you took a critical look at your backup gear? Storage vendors are proposing new iSCSI (Internet SCSI) backup devices that can make your data protection cycles faster and more flexible — and therefore more responsive to business requirements.

Generally, iSCSI-based backup solutions have a moderate acquisition price, but they work most efficiently with a separate SAN to keep traffic apart from the LAN. This increases the cost of your project, but in exchange, you get priceless peace of mind knowing added traffic won’t choke your LAN.

Moreover, you don’t need a full migration to a SAN to run backups and restores over iSCSI. You can keep your data in server-attached storage and get invaluable hands-on experience on iSCSI SANs with minimum cost and disruption, while your company thrives on faster and more flexible data protection. It’s an opportunity you shouldn’t miss.

The RA2000 d-to-d (disk-to-disk) backup appliance from Overland Storage and the Spectra 2K tape library from Spectra Logic are two remarkable examples of how iSCSI devices can respond to your company’s backup and restore challenges.

Both devices can sit anywhere on your iSCSI SAN and can connect to essentially any server, reducing the network congestion of LAN-based backups and eliminating the backup server as the single point of failure in your structure.

Besides iSCSI, the two solutions have little else in common, each fulfilling different but somewhat complementary data-protection requirements. The RA2000 appliance offers fast d-to-d backups and restores over an array of eight SATA (serial ATA) drives, which administrators can dedicate to a single server or share across as many machines.

A traditional tape library aimed at entry-level datacenters, the Spectra 2K packs as many as 30 AIT (advanced intelligent tape) cartridges and two tape drives in its midsize tower enclosure.

After using them for a few weeks, I found that the RA2000 has an edge on performance, whereas the Spectra 2K shines on management. Both share high scores for the flexibility they bring to a backup infrastructure.

REO Series RA2000

You may have seen the predecessor of the RA2000 in last year’s review of ipXcelerator from startup Okapi Software. Since then, Overland Storage has acquired Okapi and has relabeled the product line the REO Series.

Overland designed the RA2000 to buffer data transfers between backup servers and tape devices. It also created the RX2000, a 2TB expansion unit that adds capacity and speed.

The RA2000 appliance benefits from a pragmatic, browser-based management interface, which administrators can access over a separate Ethernet connection while using two dedicated iSCSI ports for data.

To set critical network parameters, such as IP addresses and subnets for the NICs, administrators can use DHCP or modify configuration files for the Linux-based appliance OS, stored on the removable SoftKey, essentially a USB drive.

The browser interface accesses only a few basic controls that include setting the iSCSI connectivity for each of the eight SATA drives, scanning for new or removed drives, and restarting the appliance. This Spartan set of controls is adequate for normal operations. But if something fails inside the appliance, the GUI doesn’t help. The RA2000 does, however, automatically send e-mails to warn of error conditions.

Interestingly, the RA2000 doesn’t enforce CHAP (Challenge Handshake Authentication Protocol) security, but administrators do have to specify which initiators may access each drive. This extra step minimizes the risk of possible break-ins but makes for a slightly more complex setup.

Speaking of initiators, the appliance now supports the easily accessible and free Microsoft iSCSI initiator software in addition to the IBM drivers from the previous version. Using the Microsoft initiators, I had no problem sharing the RA2000 across the four Windows servers I set up for this test. That configuration was easier to set up than it was to share the Spectra 2K, and with similar network and server conditions, backups and restores performed faster on the RA2000. 

For example, on Hewlett-Packard ProLiant DL360 servers with built-in GbE and Microsoft initiators, Veritas Backup Exec 9 clocked from 7MBps to 30MBps during backups, depending on the data content. Those results did not change much after adding an Intel PRO/1000 T HBA to my machines, but such an addition might benefit older sub-GHz servers.

The RA2000 presents the same improvements to backup and restore performance as its predecessor, with the additional bonus of improved scalability and a better-defined deployment. Like its predecessor, however, the RA2000 needs to be paired with a tape library to offer persistent data protection.

Spectra 2K

It’s easy to make the case for an iSCSI tape library. Normally your backup servers and tape devices are tied with the short leash of traditional SCSI cables, making for an inflexible and unforgiving setup.

By contrast, an iSCSI device such as the Spectra 2K can easily switch from one server to another over the network with no extra cables. Once your SAN is set up, there’s no need to reroute cables, and you could, in theory, run backups or restores from any server.

Unfortunately, reality suggests otherwise. For example, there’s the obstacle of the licensing scheme of your backup software: If you have to pay a license fee for each server you back up, the cost could go through the roof. I only hope that, as iSCSI libraries become more popular, vendors will find a more flexible and less punitive licensing scheme.

During my evaluation, I found a more technical obstacle to sharing the Spectra 2K: Moving the library from one server to another is not exactly plug-and-play and may require (oh, the horror) rebooting the server.

The problem seems to be that the mapping of robotics and drives is not always consistent across different software layers, iSCSI drivers, Windows Removable Storage Manager, and backup software. In some cases, I had to disable the Removable Storage Manager to get a correct mapping. A few times, power-cycling the server and library was the only way out.

A BakBone technician asserted that those inconsistencies should not appear on Linux or Unix machines, but I did not have the test bed to verify that claim. Regardless of platform, the glitches are caused in part by the convergence of layers of software from different vendors — the problem is that other products are taking a wrong shot of Spectra 2K’s hardware when suddenly switched to another server.

When I learned the work-around from the technicians, I had no additional problems. In a production scenario, I recommend switching the library only when a server fails. For normal operations, the safest way to share the library is to install client software on each server involved in backups or to combine the library with a d-to-d solution such as the RA2000.

Spectra 2K’s serial interface for the library’s initial setup simplifies entering basic network parameters, as the interface has numerous helpful commands for various maintenance tasks. In addition, the HTTP interface allows administrators to change configurations, set iSCSI connectivity security via CHAP, add users with different administrative rights, diagnose trouble spots, and monitor the unit’s performance.

The Spectra 2K is fast. In my tests, I measured a compressed backup speed close to 27MBps on a single drive — swift but still slower than the RA2000’s speed on a similar job.

The library is scalable, with a capacity ranging from one-half to six native TB, depending on the AIT tape used and the number of cartridges. With 30 cartridges and two AIT-3 drives, the unit that I reviewed is rated for 7.8TB of compressed capacity and a transfer rate of as fast as 64MBps — not bad for an entry-level library.

Conveniently, you can start from a minimum configuration, one AIT-1 and 15 cartridges on SCSI, and upgrade just about everything as you need to, including adding a second drive or faster drives, doubling the number of slots, and adding FC (Fibre Channel) or iSCSI connectivity.

In similarly grand style, the Spectra 2K offers management options — such as displaying multiple behaviors — that are usually found only on more expensive devices. For example, by purchasing the proper license key, you can switch between iSCSI and NDMP (Network Data Management Protocol), the latter suitable for backing up NAS or other compliant devices. To minimize migration problems, the library can emulate different library models or tape drives.

It’s difficult not to feel pampered by the rich set of features, good performance, and excellent management tools of the Spectra 2K. My only wishes are for a separate port for management connection and a mailbox slot to minimize door access. Otherwise, the Spectra 2K is an affordable tape library, flexible enough to adjust to the quickly changing requirements of our time.

Two Good Choices

These two devices serve complementary purposes when it comes to backing up data. The RA2000’s speed and easy setup is ideal for companies that run frequent backups and restores.

With iSCSI connectivity, the Spectra 2K can reach just about any server in your datacenter, giving the library unrivaled deployment flexibility mimicking those of more expensive FC models at a fraction of the cost. The Spectra 2K suits customers who are ready to embrace SAN-based backups but need to proceed by small, incremental steps, keeping backup and archiving capabilities in the same device.