Posted by: Dave Raffo
virtual tape libraries (VTLs)
Oracle this week made its first enhancement to the StorageTek Virtual Storage Manager (VSM) since it acquired Sun, adding a second disk tier option to the mainframe virtual tape library (VTL).
The StorageTek Virtual Library Extension (VLE) is a tier of 7,200 RPM SAS drives that lets the VTL scale to 3.5 PB of disk capacity. Previously, it supported 90 TB in one system and only Fibre Channel drives.
“We’re adding a second tier based on SAS,” Oracle tape product marketing manager Tom Wultic said. “It puts more scalability in the disk buffer at a lower price than Fibre Channel.”
The VTL extension also uses Oracle’s Solaris ZFS technology to provide Triple-Parity RAID-Z3, which Oracle claims allows five times more data reliability than RAID 6 systems from competitor IBM.
Wultic said Oracle is contemplating adding data deduplication to VSM, but isn’t sure it is necessary for mainframe systems.
“With the mainframe we expect to have lower dedupliation ratios, by nature of the product,” he said. “For example, mainframes don’t have tons of PowerPoint copies as you find on open systems.”
He also said there isn’t much demand for VTL on open systems and there are no plans to resurrect the open systems VTL platform that Sun sold using FalconStor software. Wultic said VTLs were necessary when disk backup first became popular because backup applications were developed for tape. But backup apps now work with disk as well as tape and file systems such as SAM-FS can handle archiving straight to disk.
“The time kind of came and went for open systems VTLs,” he said. “Application needs are different, so we have different ways of approaching it. For open systems, you have two use cases – backup and archiving. Backup applications used to be written for a tape image and not for disk. Over time, they saw VTLs pop up and said ‘we could do that,’ so major backup apps can now manage disk and tape. We see a trend of people using backup applications for disk instead of using a separate appliance.
“Archive applications are not written for a tape image, they want to see the file system. We have virtualization with SAM that presents a file system to those apps and has disk and tape behind it.”