Web Hosting Talk : Web Hosting Main Forums : Colocation and Data Centers : What's involved in setting up a SAN?

[nax9]

Since I can't get any answers in the technical forum, I figured this one would be my best shot.

I'm looking at using SAN storage for multiple webservers, and I'm slightly confused about something.. if a SAN comes with a controller, doesn't it still need a RAID card (I'm looking at making the SAN robust AND quick)?

I know about the bare-minimum gigabit ethernet/fiber along with how to load most things. It's just the barebones hardware I'm having trouble wrapping my head around.

thanks for the help guys

[Webdude]

There's a reason it doesnt get answered. People dont like looking stupid, so lets see how stupid I can make myself out to be.

Short answer is no, but obviously this is not the case with all sans. Depends on the manufacturer or if you build your own. If you purchase a more modern one that is already an all in one solution, then your answer would be no, you do not need a seperate raid card unless you adding something to the array outside of the normal parameters which would require one (eg: external tape drive, etc)

[Spudstr]

Traditional SANS work off FC or known as Fibre Channel. Servers are equiped with HBA (host bust adapters) which in turn connect to a FC/SAN switch fabric, speeds of 1,2,4,8Gbps. Most SANs are dual controllers. And no you can't just build your own FC SAN.

Though you can run FC over IP its not recommended.

Now build your own solutions would involve ISCSI Sans. These are cheaper, you can use a normal server and create a target, use solaris ZFS + iscsi theres a slew of things that you can do. IBM/Hp/dell etc all use LSI controllers to build their Iscsi systems that are dual controllers.

FC or ISCSi you cannot share LUNS between servers unless you have some sort of file locking controller/software that controls locking.

SANs are great for blade servers etc that can't have mass storage attached to the servers. The ability to create luns on raid groups to distribute IOPS like VMware does virtualization of CPU's across a few CPU's

[JTY]

Most SAN storage units implement RAID within the storage unit's controller, so the servers accessing it don't need a RAID card.

[bqinternet]

For a simple redundant SAN, just get two iSCSI targets and do mirroring at the host level with something like LVM.

[KayakStudio]

i'm no expert but wouldn't NAS work just fine and perhaps be easier?

[JTY]

A NAS would work, but it's not likely to scale or perform as well as a SAN.

[dkitchen]

Originally Posted by KayakStudio

i'm no expert but wouldn't NAS work just fine and perhaps be easier?

You won't get quite as good performance from a NAS solution, among other things. You are also unlikely to be able to offer the same level of availability with a NAS solution (a SAN will usually have two SP's so it is fully redundant).

In most cases you want to keep your storage network separate from your data network anyway.

[Spudstr]

NAS = shared file system
SAN = block level

[KDAWebServices]

Originally Posted by Spudstr

NAS = shared file system
SAN = block level

Not quite, a NAS filesystem doesn't have to be shared at all, I think what you mean is that a NAS works at a file level, but a SAN at the block level.

[Spudstr]

Originally Posted by KDAWebServices

Not quite, a NAS filesystem doesn't have to be shared at all, I think what you mean is that a NAS works at a file level, but a SAN at the block level.

Right.. a "NAS" isn't really a file system it just presents the current file system that can be mounted and the locking is controlled on the host machine still..

there for NAS operates at the file level, and a SAN operates at the block level when it comes to locking.

[KDAWebServices]

Well technically it is, it doesn't export raw LUNs/Volumes, it has to have a file system to work at a file based level, it's just that you're not mounting the file system, you're dealing in file shares.