Data-protection methods that rely solely on tape devices will someday appear as inadequate as using two tin cans and a string for telephony. That day could be sooner than you think, as companies seek more flexibility in backups and demand more speed in data recovery than tape-only solutions can deliver.
The two data-protection appliances reviewed here, Storage Technology Corp.’s (Storagetek’s) EchoView 400 and Okapi Software Inc.’s ipXcelerator, both leverage iSCSI connections and disk-to-disk copies to improve data protection and make recovering from data loss faster and easier. The similarities end there.
Okapi Software’s ipXcelerator takes a more traditional approach to backup, sitting between your servers and tape devices to make backup and restore cycles speedier and more flexible. It even allows you to use your favorite backup software.
By contrast, the StorageTek EchoView 400 aims to provide nearly continuous protection of your data. The EchoView creates an initial copy of each protected volume and keeps a log of changes at intervals as short as every 30 seconds. In addition, EchoView groups those changes according to user-defined schedules, in volume images that administrators can easily restore in case of corruptions.
Depending on the data-protection problems that you wish to solve, you may need one or the other — if not both — of these solutions. If having a faster backup and restore cycle is your recurring dream, the easier-to-deploy and less-expensive ipXcelerator fits the bill. However, if you need a system to recover up-to-the-minute images of your volumes, EchoView deserves your attention.
Constant Watchdog
The EchoView appliance is a central repository that hosts images of your server volumes captured by client software installed on each server. In addition, the client intercepts volume changes and transfers them every 30 seconds to the appliance via a dedicated GbE (Gigabit Ethernet) connection (the “Echo” connection). A second GbE connection (dubbed “View”) to the server can be used to restore point-in-time copies of each volume from the appliance. This gives administrators an exceptional level of flexibility to recover from recent data corruption without wasting disk space on older views.
Similar to implementations in other commercial products and in open source file systems, EchoView’s change log approach offers undeniable advantages over snapshots. In addition, EchoView’s unique twist on user-driven consolidation allows frequent recovery points for recent history and a space-saving, automated synthesis of older history that administrators can easily adjust to business and application requirements.
I reviewed one of the first EchoView appliances, which packed two Pentium III processors and six 73GB Quantum Atlas 10K III SCSI drives (now manufactured by Maxtor) in a 2U, rack-mountable chassis. The unit was also equipped with redundant, hot-swappable power supplies and five Intel PRO 1000 MT NICs, each with two RJ45 connectors. EchoView uses these five pairs of NICs to connect Sun Solaris or Microsoft Windows servers.
To prepare my two Windows 2000 servers to connect to EchoView, I installed one Intel PRO NIC (for the Echo connection) and one QLogic HBA (for the View) on each machine, and then made point-to-point connections between the servers and the appliance.
The setup process is quite complex. For each server, you must assign four interdependent IP addresses, install the client software, set the iSCSI connections, choose the volumes to protect, and define the recovery policy. Luckily, the EchoView Web-based management GUI automates many of those activities, including the iSCSI configuration.
Once my setup was complete, the EchoView client began sending an image of the protected volume to the appliance, a process that took less than four minutes for a 4GB volume containing 900MB of data. After that initial copy, the EchoView client went into sleeping mode, waking every 30 seconds to report volume changes to the appliance over the Echo connection.
From EchoView’s management GUI, I was able to view the volumes that EchoView had already created on the appliance, spaced at 30-second intervals. And using the EchoView client, I was able to restore them to a different volume. As expected, those views were exact replicas of my original volume at the specified point in time. Once the continuous protection time expired, I could view older versions of the volume, spaced at eight hour intervals, as defined in my protection policy.
EchoView is a challenge to set up, and a few pieces have yet to fall into place. But it provides rock-solid recovery capabilities and unique flexibility in adapting to business requirements. Combining speedy recovery from data corruption, nonintrusive offline backups, and the capability of assigning volume images to other applications, EchoView should have bright future.
Faster Backups
Unlike the EchoView, Okapi’s ipXcelerator doesn’t seek to provide more granular recovery capabilities, but to provide faster, more flexible backup and recovery by replacing slower tape devices with iSCSI-connected disk drives.
The 2U, dual-processor ipXcelerator mounts up to eight SATA (Serial ATA) drives attached to a 3Ware Escalade controller. The drives can be configured as independent JBOD (just a bunch of disks) or RAID 1, for a total capacity is 1.6TB. The ipXcelerator reaches out to servers via two GbE data ports, while an additional Ethernet port connects the appliance to the LAN.
Obviously, you will have to install a dedicated GbE card and the IBM Corp. iSCSI drivers (included with the appliance) on each connected server. Depending on the number of disks and their configuration, the ipXcelerator can be the backup target for up to eight Windows 2000 or Windows Server 2003 servers, using switched connections to its two GbE cards.
How much faster will your backups run using ipXcelerator? Again, it depends. If tape devices or network connections are the slow link in your backup chain, expect a significant improvement.
For example, using Veritas Software Corp.’s Backup Exec 9 on an idle Hewlett-Packard Co. ProLiant ML350 server and targeting a single ipXcelerator disk, I measured average backup rates in the range of 7MBps to 17MBps. Naturally, concurrent activities or slower disk devices on your server can reduce that performance gain.
However, ipXcelerator can deliver benefits such as saving media-handling time and evenly distributing backup jobs across your servers, even when your servers are the slow link.
Compared to the stormy EchoView installation, setting up ipXcelerator was smooth sailing. A flash card inside the appliance hosts the Red Hat Linux OS, reserving precious disk space for data protection only. In addition, a USB drive, the ipKEY, plugged into the back of the unit, has the dual purpose of preventing configuration changes (when removed) and storing network settings.
Backing up to the appliance is intuitive. I launched Veritas Backup Exec 9 (already installed on my server) and added a “removable backup to disk” folder to each removable disk. Next, I created and ran a backup job using the new folder as target device, which worked as expected, only finished sooner.
Plus, Okapi includes software to safely access the same iSCSI disk from multiple servers: you only have to include two snippets of code (they will act as a traffic light on your iSCSI connection) in your backup or restore script.
Running restores was equally easy, with the additional advantage of not having to look for the tape media to mount. It’s easy to get used to not using tapes; actually, it can be addictive.
Although deploying ipXcelerator involves modifying your backup scripts, I have otherwise only positive remarks from my experience with the product. It’s relatively easy to set up, it can adapt to just about any backup requirements, you can easily scale by adding more units, and it’s price competitive with midrange tape autoloaders.
If your backups are slowing down your business, consider Okapi Software’s ipXcelerator before ordering faster tapes.
