Data Storage - Difference between SAN and NAS

Author

Difference between SAN and NAS

g18c@hotmail.com

2006-07-30, 1:13 pm

Hi, im thinking there is not much logical difference between a SAN and
NAS in a small business environment.

For example, say i have a file server which connects to a SAN. I have a
number of drives defined in the array and then expose these drives and
share them through samba. Now my network users connect to the server
which connects to the drive array. No problem, but this is the same as
NAS, so be it a stupid question, for a small setup as above NAS would
be better correct? I guess the only advantage of SAN is that you would
have the ability to use built in security of the servers OS rather than
relying on features of the NAS server?

Reason i ask is i need some large network storage cheap, and the
previous manager i took over from defined a GBP 35k storage 2TB
solution which im thinking is a little bit steep!! NAS with Raid 5
would be sufficient, and much much cheaper, however i like the idea of
SAN for expandability.

Thanks in advance for clarifications and recommendations!

Chris

Faeandar

2006-07-30, 1:13 pm

On 30 Jul 2006 08:23:37 -0700, g18c@hotmail.com wrote:

>Hi, im thinking there is not much logical difference between a SAN and
>NAS in a small business environment.
>
>For example, say i have a file server which connects to a SAN. I have a
>number of drives defined in the array and then expose these drives and
>share them through samba. Now my network users connect to the server
>which connects to the drive array. No problem, but this is the same as
>NAS, so be it a stupid question, for a small setup as above NAS would
>be better correct? I guess the only advantage of SAN is that you would
>have the ability to use built in security of the servers OS rather than
>relying on features of the NAS server?
>
>Reason i ask is i need some large network storage cheap, and the
>previous manager i took over from defined a GBP 35k storage 2TB
>solution which im thinking is a little bit steep!! NAS with Raid 5
>would be sufficient, and much much cheaper, however i like the idea of
>SAN for expandability.
>
>Thanks in advance for clarifications and recommendations!
>
>Chris

The main difference between SAN and NAS is access type. SAN is block
access and NAS is file access. There are other variances too, like
security, but access is the biggest.

If your goal is file sharing then NAS is the way to go. You could
build a SAN, attach hosts to it, then share the file system out for
NAS access, but that's alot of work and cost (not to mention
complexity) just to get file sharing.

And yes, 35k for 2TB of storage is ridiculous for what you've
intimated.

~F

g18c@hotmail.com

2006-07-30, 7:13 pm

Thanks for the reply. Ive gone for a HP ProLiant DL380 G4 server as we
already have an HP rack and HP server domain controllers. It fits the
bill nicely, and comes in at GBP 5,500 with 2.5TB of disk space.

I was thinking of going for an Adaptec SnapServer but they seem quite
expensive, the HP comes in at a few k less, however HP server runs
windows which is another thing to screw up :3).

Either way i've looked into iSCSI and it sounds ideal later when i want
to run mail server storage... i now see the benefits of SAN when you
have multiple servers needing storage space - ill be able to get good
utilisation out of my disk drive space :3). Whilst we currently do not
have a need we will in about 3 months so SAN will definetly give me
flexibility.

HP good/bad? Any reasons why Adaptec would be better? With HP i will
have 7 bays free whereas the Adaptec only 2... another reason i chose
HP. Comments most welcome.

Cheers,

Chris

Bill Todd

2006-07-30, 7:13 pm

g18c@hotmail.com wrote:
> Thanks for the reply. Ive gone for a HP ProLiant DL380 G4 server as we
> already have an HP rack and HP server domain controllers. It fits the
> bill nicely, and comes in at GBP 5,500 with 2.5TB of disk space.

Even that seems a bit pricey for serving just a couple of TB of storage:
unless it's really heavily used by many concurrent clients a
single-processor box should be more than adequate (especially given the
inexpensive dual-core products now generally available). But perhaps
you have ambitious expansion plans.

....

> however HP server runs
> windows which is another thing to screw up :3).

Well, there's nothing stopping you from running *BSD or Linux on it,
though HP may not give you any help on the software end if you do.

> Either way i've looked into iSCSI and it sounds ideal later when i want
> to run mail server storage... i now see the benefits of SAN when you
> have multiple servers needing storage space - ill be able to get good
> utilisation out of my disk drive space :3). Whilst we currently do not
> have a need we will in about 3 months so SAN will definetly give me
> flexibility.

You'll have to have a very definite requirement for flexibility to
justify the additional cost (both in hardware and in management) of a
SAN (even an iSCSI SAN): given how inexpensive directly-attached
storage is these days, it almost doesn't matter how well it's utilized
(and even if you leave a fair amount of space idle on some servers the
extra disk arms still help performance while isolating the servers from
interfering with each other in that regard).

>
> HP good/bad? Any reasons why Adaptec would be better? With HP i will
> have 7 bays free whereas the Adaptec only 2... another reason i chose
> HP. Comments most welcome.

If you're dead set on moving to a SAN soon anyway, free bays wouldn't
seem to matter much. If you stick with directly-attached storage, you
might want to look for boxes (or expansion boxes) with lots of 5.25"
bays that you can install hot-swappable drive caddies in, plus the
software to RAID them.

- bill

g18c@hotmail.com

2006-07-31, 7:14 am

> Even that seems a bit pricey for serving just a couple of TB of storage:
> unless it's really heavily used by many concurrent clients a
> single-processor box should be more than adequate (especially given the
> inexpensive dual-core products now generally available). But perhaps
> you have ambitious expansion plans.

Thanks for the pointers. As the disk requirements are likely to grow in
stages upto a multi server disk solution im going to use the DL380 as a
NAS server with SMB shares initially. Once i start using Exchange, and
running the SQL databases i think the solution will allow me to scale
the drive requirements. At that point i can buy some extra disks (only
GBP140 per 250GB), add the iSCSI addon HP pack and ill be away
laughing. I agree putting fixed arrays in each computer is a good idea
and much cheaper, but IT is my secondary function really and i dont
want to be messing about sorting out individual raid arrays for each
server (in the long term we will have around 6 servers requiring
redundancy, keeping the RAID in once place will be boon in terms of my
management time, my time is money and all that and it may work out
cheaper in the long run). Thats the idea anyways.

Thinking about it ive just answered my own original question!! I'll use
NAS for the time being, and grow to SAN once i have the servers in
situ.

Thanks again guys.

Chris