SATA/SAS vs plain SATA; Cost Per GB - What am I missing?
Posted on 2007-07-20
I am looking to upgrade our current storage systems in a few of our locations from about 300-500 Gb to 2-6 Tb.
Everyone that I talk to tells me I should go for a high end, but basic, SATA RAID array using a few 500Gb disks. If I start talking scalability, they start talking about fiber channel, but warn me against the high costs involved. Every time I mention SAS, I get warned against it, for it being either more expensive and complex than FC, or just that it's a "fancy new toy, but not as good as FC".
I feel like I'm really missing something here....
It looks to me like, assuming I am going simply for capacity and not extremely high availabity, that I should be able to host, on a single 8 port SAS card, an array easily scalable to over 60 Tb of storage for around $0.58 per Gb. (*) What's more, it appears that the overall cost will scale in a linear manner if I need more or less storage space...
(*) Assuming the following:
1 eight-port SAS card: ~$1000
8 12x SAS Edge Expanders: (1 host <-> 11 devices) ~$8000
88 750Gb SATA disks (**): ~$25000
11 basic 8-disk SATA ensclosures: ~$2500
Misc cabling and adapters: ~$2000
Storage: 66000 Gb
Cost per Gb $0.5833
(**) I'm going with the assumption that you CAN use SATA disks within an SAS array... Everything I see in the specs indicates that you can, and since I'm only looking at capacity, I don't need the dual-port redundancy available to SAS drives.
Note, of course, that I only need 2-8 Tb in my arrays initially, something that can easily be taken care of with a standard SATA RAID controller. But I like the idea of being able to scale... The entry costs to SATA and SAS appear very similar when using SATA-only drives, and the overall costs appear to scale in a linear manner.
What am I missing? Why do OEM builders and other sysadmins shy away from SAS? Is it just because SAS equipment is so new? Is there something unusual about the way SAS cards interact with their arrays?
I can build the array I noted above, right?
Any input would be appreciated; thanks in advance.