If you have a database running in a SAN then backing it up can cause problems. If you back it up direct to tape then you have to quiesce the database, stream it to tape which can take hours, and then fire it back up. In today's increasingly 24x7 world that's becoming less feasible, even if you do have lots of concurrently active drives.
To avoid halting the database a common tactic is to buy a second disk array and then copy the database to it. The copying takes minutes instead of the hours needed for a backup, and you can backup to tape in comparative leisure from the second array. It's costly, no doubt about that, but you do get out of the backup window bind. It’s overkill though because you don't actually need the random access speed of the second array; all you need is the streaming speed.
It turns out that ATA drives, with the requisite controller can stream about as fast as a fast array with SCSI drives. Enter Bladestore, which is a much less expensive second array, using such ATA drives.
Its random I/O speed is less than the fast array but it’s not an issue. All we wanted to do was stream database copies from the production database and then on to tape. It sits between the production fast arrays and a tape library and provides an intermediate staging area with all of the advantages provided by a second fast array but none of the disadvantages.
There is a controller, almost identical to the controller used in Storagetek's high-end D Series arrays, and rack shelves of ten disk blades, about 6U high and mounted vertically with five drives per blade, 250GB Maxtors, in our case. The supplier physically installs the kit and leaves it network-connected and ready to run. The first job is to configure it and then connect it to servers that can use it.
SANtricity management software is used for this and wizards are used on our Windows 2000 host to accomplish the tasks. The SANtricity software auto-discovered the new array and produced its IP address. We then set up a logical disk, a volume, with a RAID 5 configuration, and the controller then formatted the disk. The time taken for this depends upon the size of the volume; the larger the volume, the longer the time. It’s inescapable.
Once that was done we connected the volume to a server. We could connect it to a specific server port or to a group of servers if they were all going to access the array. Now we were in business. The server could see the volume and we then used Legato Networker to copy the database.
Configuring Bladestore took about ten minutes. It will take longer the more volumes you set up and the larger the volumes; but that's formatting time.
The management software presents a recognisable schematic diagram of BladeStore with controller, shelves and disks identified. The disk icons are coded to indicate their status: green for okay for example; and other variations for used and unused hot backups; and so forth.
We found that controller modules were duplicated as were fans. A controller or fan failure wouldn’t be catastrophic. Everything was well-made and fitted together and the system was very easy to set up. No training course is needed and an average adminstrator experienced with managing disk arrays should have no trouble at all.
BladeStore isn’t for use as a production database array. But it can release a second fast array, just used as a backup cache in our case, for production use.
What the net of this is that we would be able to reduce the size of our tape library and the number of drives in it, as we had several copies of the database on BladeStore and restored from there. The tape copy would become the copies of last resort whilst everyday restores would take place from BladeStore. As a by-product the released second fast array can join the production array and provide expansion space if needed. It was not wasted.
This relatively short review can't do full justice to the product which can scale to 150TB and stream data at around 400MB/sec through its Fibre Channel ports.
We recommend BladeStore as a prime product to be considered where you have a production database array and quiesce your database to back it up to tape. BladeStore’s cost can be recouped in avoiding the time when your production database isn’t online due to its data getting protected.
Buy BladeStore if your production database, sitting on a fast drive array, costs you money while it is offline being backed up to tape.