The south Kent council has 500 employees and 70 servers running applications such as Northgate CRM, revenue and benefits software, CAPS UNI-form planning software, Microsoft Office and Outlook 2003 email. When the local authority experienced expansion in its planning department and also brought in-house a number of outsourced services, the number of its servers swelled, forcing the IT department to look at its backup arrangements, says Steve Makin, ICT network services manager at the council.
According to Tracey Boyle, network support officer at Shepway council, Symantec was also rejected on grounds of poor support. "We were also reluctant to go with Symantec because their helpdesk service was appalling," she says. " We'd log a call and we sometimes weren't getting a response for a week. And with something like backup that's not acceptable."
The Bakbone software now backs up data to disk and then tape in a D2D2T configuration. Data is first backed up to a Nexsan SATAbeast array with 14 TB of capacity in which storage is provisioned – including to a virtual tape library -- using Datacore SANMelody software. Backups to the Qualstor tape library then take place via a separate non-production area of the storage network.
The council runs full backups at weekends with differential backups running every evening. The key benefit for the council is the shortening of the backup window, says Boyle. "The amount of data we can back up and the speed is incredible," she says. "We are backing up just 1 TB to 2 TB in differentials every night with eight servers being backed up to the VTL at a time."
Boyle says she initially found the restores from Bakbone "a bit cumbersome." With Symantec, she says, "all we needed to do was restore from one tape. With Bakbone we need all the tapes, but it's only a minor difference as we do get a very quick restore time."
Disk-to-disk-to-tape is a method that allows users to shorten backup windows by making use of faster throughput speeds from disk to disk than that of disk to tape. Instead of writing directly to tape, backups go straight to nearline disk – often formatted in ways that emulate tape as a virtual tape library – and are then archived to tape at appropriate times. Benefits include quicker backup and restore times – because they are straight from disk – and potential for decreasing the load on the network and the backup and media servers.
Possible drawbacks with D2D2T include the addition of an extra point of potential failure into the system. Also, the step from disk to tape, if not using the backup software, can add extra complexity. The latter can be the case if the D2D2T appliance moves data to tape and the backup software has no awareness of the image stored there.
It will sometimes be the case that restore from tape will have to pass through the secondary disk before returning to the production environment, but that shouldn't be a problem most of the time, says Tony Lock, programme director with analyst group Freeform Dynamics. "It is adding a layer of complexity to put in an extra tier of disk," he says. "But that's not a problem in most cases as the majority of restores are those that tend to be required quite soon, for example when a user has mistakenly deleted something. You will need more disks for D2D2T and disks cost more to buy and to power than tape, which is a consideration when some are looking hard at their power bills and trying to reduce them."