[Ma-linux] Re: [Novalug] Loaded question about SANs, but here goes

Jason novalug@jasons.us
Sat Mar 17 15:12:07 EDT 2007


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Jay,

Define "BIG BIG".  The smallest system you'd get from a NetApp, EMC, etc
would be in the several terabyte range.  If you want to roll your own
five 750GB SATA drives will give you a RAID5 with 3TB of usable space
and that'll fit easily inside a single box.  Some of the larger server
cases will hold up to eight drives for over 5TB usable.

You mention that there will be multiple servers accessing this data.  Do
you intend for them to each have their own, exclusive space within the
storage system, or will it be shared storage?  To summarize what Chris
explained earlier a SAN is basically a big storage system (one or more
RAIDs) that can be divided up into smaller parts, each of which is
assigned to a particular SAN client - one of your Dells.  (I'm leaving
out things like shared SAN filesystems because they are way too complex
for this situation.)  It's very similar to attaching a smaller RAID to
each of your servers - sharing between them is tough.  The main thing a
SAN gives you is flexibility in that you can buy 20TB of storage and
give 2TB to 5 systems and save the other 10TB for growth.  And then if
server2 doesn't need the full 2TB you can take some of that storage and
put it back into the general pool.  In exchange for that flexibility is
complexity and cost.  SANs are usually faster than locally-attached
RAIDs, but that depends highly on the configuration and use.

Now, if you want there to be shared storage between the servers you'd be
better off with a NAS device: basically a RAID with a NIC that uses NFS
and/or CIFS to communicate with the clients.  You can run databases on
NAS, by the way.  Oracle certifies their system to run on NetApp, for
example.  NAS is a bit slower than SAN, but unless you're pushing the
edge of performance or QOS you won't really notice much.

If you intend to buy a SAN to play with you should look at one of the
smaller vendors like QLogic - their switches and HBAs tend to be cheaper
than the Ciscos and Brocade/McDatas.  But if this is just an academic
exercise your options are much broader.

In short, a SAN is little more than a "BIG BIG disk array".  The
question is what you want from a SAN that you don't get from
locally-attached or even NAS storage.

- -Jason, Storage Systems Engineer (eg: NAS/SAN/Backup geek)

PS: My ma-linux subscription address is different from the one I use for
novalug so if the ma-linux admin would kindly allow this through I would
appreciate it.

Jay Hart wrote:
> I'm developing a "enterprise" level solution, in a class room setting, so budget is no concern.
> 
> I'm not sure that I need a SAN, what I am looking for is a seamless way to store many types of
> data files, be it video, audio, html, XML, databases, etc. The app going to get the data should
> not have to worry about location of file or file type, if possible.
> 
> The system will have over 300,000 users, and so whatever we put together must be fast, reliable,
> secure, and have redundancy built-in.  The servers will be Dells running RHEL AS5, with the app
> written in JBoss.  The database app will be a big Oracle DB running on the servers, and we thought
> the the DB itself would be hosted on the SAN (???). Other data needed by the app would also be on
> the disk array / SAN.
> 
> So, can I get away with just a BIG BIG disk array??
> 
> Jay
> 
> 
>> Jay,
>>
>> I am a former HP storage consultant so I can bore you to death about SANs.
>>
>> I guess the first question is what is you budget and backup requirements?
>>
>> iSCSI or Fibre Channel?
>>
>> -brian
>>
>> On 3/17/07, Jay Hart <jhart@kevla.org> wrote:
>>> I have a grad class in which I am developing a online information
>>> system.  As part of this system
>>> I want to store all my data on a SAN (storage Area Network).
>>>
>>> I am trying to research what hardware to buy, but I'm not sure of what I
>>> need.
>>>
>>> So, (here is the loaded question), can someone out there who might be
>>> using a SAN, or has looked
>>> into buying a SAN, point me in the direction of what hardware I need.
>>>
>>> Criteria:
>>>
>>> 1. Servers intrefacing this SAN will be running RHEL
>>> 2. Oracle Databases will be stored on the SAN
>>> 2a. Files (video, audio, text-based, etc) will be stored on the SAN as
>>> well
>>> 3. I want to try and keep the hardware platform simple
>>> 4. If I have missed something please let me know


- --
- -Jason

- -----
   --- There are no absolute statements.  I'm very probably wrong. ---
"The difference between genius and stupidity is that genius has its limits."
                                        - Albert Einstein
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