The backup costs per server on a SAN appear to be very costly. We can justify the costs of a SAN if we look at server consolidation as our measuring stick. However, the infrastructure costs of adding each server appears to be cost prohibitive.
We are currently looking to purchase a SAN from Xiotech. As we add each server to the SAN Fabric, it looks to cost upwards of $8,000. This could easily take out our ROI. We use a Quantum tape library with ArcServe Enterpise to backup our systems. We already own the Library and the Arcserve Enterpise edition.
We are being told that each server needs to connect to the SAN via a Fiber switch, $2,200 for two ports on an eight-port switch and two connections per server for redundancy. We need an "Arcserve for SAN" license for each server ($1,600), yearly maintenance on the backup software ($600 SAN option), and an FBA card for each server ($500 - $2,000, I am using the higher number of 2k).
This comes to approximately 8K of additional costs for each server.
The plan is to add an additional tape unit to our current tape library system that is a Quantum 3100 using LTO tape technology. Continue to hang that library system off from a dedicated server attached to the SAN fabric.
My proposal called for an initial setup of four servers, the SAN fabric, the tape library and the SAN itself. However, as I looked at how I would add another 10 to 12 servers and back them up, it is becoming much more costly. (10 servers @ 8k = another 80k).
Can our vendor be correct? Is there a better way?
Not every one of your servers needs to be connected to the SAN for backup. You are correct that after all the hardware is bought and licenses paid for, SAN backup costs can add up very quickly.
Here is my prescription for SAN backup:
1. Consolidate your server environment using clustering for better availability with fewer servers.
2. Only incorporate servers into the SAN for SAN backup that are critical servers or have tons of storage requirements. These high capacity servers will kill your network if you back them up over the LAN.
3. Use SAN based storage for file services if you can. File services are one of the biggest consumers of storage. Use clustered servers connected to the SAN to share out file/print or use a SAN connected NAS device. This will enable you to back up all file/print and SAN storage from the same place over the faster SAN.
4. For remote servers, if your network supports it, use iSCSI connections into the SAN to consolidate backup across the enterprise.
5. If you find SAN backup licenses to be too expensive, install a separate Gigabit Ethernet network between your critical servers and use that separate network for backup.
6. There are other tricks you can do but space is limited here. I cover most of this in my up-coming SANs for dummies book that should be available in March.
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This was first published in January 2003