Edit: SVC is still here, and the links still work.
Originally posted June 17, 2008 on AIXchange
For many system administrators, SAN management is like an unsolvable mystery. The fibre cable is plugged into the server’s host bus adapter, and then somehow, like magic, a LUN appears. Others who more frequently interact with their disk vendors are involved with disk management on an ongoing basis. Although I’m usually more OS-centric, I understand that disk subsystems hugely impact system performance and data availability. I know that the world’s fastest processor does me no good if my disk subsystem isn’t sized appropriately.
When disk subsystems get refreshed, questions crop up. What’s the method for migrating from an EMC disk subsystem to a new IBM disk solution? Should you back up your data from one storage unit and restore it to another using tape? Maybe you should export a LUN from the old and the new disk units and then mirror them using LVM in AIX. What if you want your production data to be stored in a new disk subsystem, but you also want a flash backup copy of it so that data is available on older, slower disk?
If you’re unfamiliar with IBM’s SAN Volume Controller (SVC), get to know this product. IBM’s recent announcement of SVC Version 4.3 is a good starting point.
According to the announcement, SVC allows you to:
- Combine storage capacity from multiple vendors for centralized management.
- Increase storage utilization by providing more flexible access to storage assets.
- Improve administrator productivity by enabling management of pooled storage from a single interface.
- Insulate host applications from changes to the physical storage infrastructure.
- Enable a tiered storage environment to match the cost of storage to the value of data.
- Apply common network-based copy services across storage systems from multiple vendors.
- Support data migration among storage systems without interruption to applications.
More from IBM:
“System Storage SAN Volume Controller Software in version 4.3.0 further extends its dynamic and high availability storage management capabilities with the introduction of space-efficient VDisks and VDisk mirroring functions. Space-efficient VDisks add the capability to define virtual disk capacity that is separate from the physical disk capacity, and use only the physical disk capacity required to store the data.
“VDisk mirroring offers a significant improvement for high availability SVC configurations by providing the capability to have a VDisk supported by two sets of physical managed disks (MDisks) in different managed disk groups on different storage controllers.
“SVC copy services are further enhanced by allowing FlashCopy to be used with the new space-efficient VDisks to yield a space-efficient FlashCopy capability, which combines with the support for up to 256 FlashCopy targets to enable more frequent FlashCopy while improving physical disk usage.”
For a basic introduction to the SVC, there’s always Wikipedia:
“SVC uses an in-band architecture which means that data flowing between a host and a storage controller flows through an SVC node. On the front end, SVC presents an interface to a host which looks like a storage controller (like a target). On the SVC’s back end, it provides interface to a storage controller that looks like a host (like an initiator).
“SVC holds the current Storage Performance Council (SPC) world record for SPC-1 performance benchmarks, returning over 272K iops (release 4.2.0). There is no faster storage subsystem benchmarked by SPC. The SPC-2 benchmark also returns a world leading measurement over 7GB/s throughput.”
Many of you might be thinking, “I’m a system admin, not a storage guy.” But outside of large specialized environments, the system admin and the storage guy are often the same person–or at least they work closely together to keep the organization’s data accessible and available.
So, chances are, making disk administration easier and data more highly available in your environment is part of your job. Check into the SVC and see if it can help you.