SAN vs NAS-Secure Data Storage for Small Businesses?

DeePCedure asks: "I'm the network administrator for a small e-commerce solution provider that is growing very quickly. We need a host independant means to centralize our data storage, but we have multiple platforms including Linux, Win32, two generations of Mac's, BeOS, and even OS/2. A Storage Area Network(SAN) seems like the best solution, but most of the information I've found on SANs is geared toward large enterprises. Also, Fiber Channel technology being as expensive as it is, a SAN seems out of reach. Network Attached Storage(NAS) is probably the next best thing but NAS has it's own problems. Most of the devices I've found don't support all of our platforms, and the ones that do don't have very good security. How can I centralize ~100GB of data on a multiple platform network within budget? Also, how can I do it securely, with controlled access all the way down to the bottom level of the data structure? "

Comments

Roll Your Own, but You Lose Alot

[Bryan Andersen]

This may end up being the solution to stay under budget, but you do lose alot going this way. One thing is well integrated automated backups. Some of the NAS and SAN products have very good backup abillities built in. Even on an hour by hour basis. Great for those absent minded users who delete critical reports just before they are due.

If you decide to roll your own a few things to remember:

• If you use mirrored RAID, place each image on separate SCSI controllers. This way a SCSI controller can die and the system can continue to work.
• Lots of RAM for disk caching.
• A mirrored/stripped RAID setup will have lower CPU overhead than RAID 5, but if your CPU is very fast this may not be a factor.
• How you stripe your disks is important.
• Don't skimp on RAM volume. Buy lots of it. you can skimp some on speed but only if you are doing it to get more RAM for the same cost. Your RAM speed isn't the bottleneck, your disk controllers, harddisk, and network speeds are.
• For any mirrired or RAID setup buy a few extra disks for replacements, then mount them in the chasis. Hook one disk per SCSI controller up to power and the SCSI chain. It will be your "hot" backup disk. If possible have it not spin up. note you will need to have software to tell it to spin up when it is needed.
• DLT tapes are your friend, and place them on their own controller. They are fast, and hold large amounts. Even at 600MB/minute it still takes a long time to backup 100GBytes. 2:51 assuming you get full transfer speed on the tape. It would be better to plan 6 hours per backup and a robot tape switcher from the start.
• If you find out backups take longer than you can have the system down. Consider a third set of disks that can be a backup set where you do a copy to them each night, then backup durring the day.

I hope this helps some. In the long run I feel you will likely be happier with a NAS or SAN system.

A possible trick

[Bryan Andersen]

I just remembered that at one of the former places I worked they used an intermediary system to allow some really old systems to be served by their main SAN array. Doing something like this may be a possibility to handle systems unsupported by a NAS system. I'd first check to see if it was possible, but it's worth a try. The intermediary system served an old network file system format to the old boxes while actually getting the files via NFS from the SAN system. It did slow things down some, but it worked.

Cross platform SAN not here yet

[Anonymous Coward]

We've looked at NAS (Network Attached Storage) vs SAN (Storage Area Network) lately. I'm certainly not well versed in these technologies but it seems to me that to go with a pure SAN, that is, fibre channel from the disk array to all hosts, with all hosts writing to the same filesystems, there are no good cross platform solutions. Megadrive has CDNA that will be cross platform, I've heard they have linux support now, beta NT, with Solaris due in the summer. Achieving a cross platform SAN solution in this fashion is quite challenging given that in a pure SAN locking mechanisms have to be implemented on the device rather than mediated by a host's OS. Thus, you need a new filesystem and weird VM layer things, that's probably why linux was done first, its VM layer is pretty clean so that it can support other filesystems. So most solutions tend to be proprietary, ergo, single platform. CDNA buys you nothing for the number of platforms you want to support anyway, you'd still have to gateway to them, you're back to doing file service from a host.

If you don't need all hosts writing to the same filesystems, then of course you can partition the storage up. A SAN wouldn't be very cost effective for 100GB, given that you have to get the fibre hubs and adapters, this would be a significant fraction of the cost of the actual storage on a SAN of that size.

With NAS you just use your existing infrastructure. The NAS idea is kinda nice, simple to maintain, plugs right into your network, good performance. We looked at Network Appliance their stuff can do NFS and CIFS/SMB. Its not all that cheap either but more cost effective that a 100GB SAN.

NAS more mature...

[cmaxx]

*cough* let me try again.

NAS is more mature than SAN, also SAN products aren't and won't become available for some of the platforms mentioned, of that I'm confident.

My suggestion would be to use a low-end NetApp if it's in the price-range or a Solaris x86 box coupled with a RAID system like the Arena boxes you can get from Zero-D.

NetApp gives you the gamut of NAS facilities, including snapshots, RAID, Integrated Unix and NT permissions, and your choice of access protocols.

The x86 option lets you build your own, exactly as you would with Linux or Freebeard, but also nets you a working lockd, and a comprehendable, consistent, and on-line tunable system, including the network stack.

Obviously someone is going to flame me for this, but I'm wearing asbestos undies. 8)