Post reply

Clustering questions for getting started

  • October 18, 2005 at 9:01 am

    #91834

    I have been doing some research about clusters, SANs and SQL Server as part of my SQL Server administration self training (I have been a SQL Server developer since v6.5).  I have come up with some questions that I have a hard time finding straight answers for:

     

    1)      Is a SAN just a computer running the RAID array to share with the nodes?  If so, why do they normally cost about $10K+?  Can you build one yourself with just a server and some RAID cards that have external ports?

    2)      What happens if the SAN goes down?  Doesn’t the entire cluster go down?  Doesn’t that make it so that if one machine, the SAN, in the cluster fails they all fail?  Why is that better then no cluster at all?  Seems bad to me – I would rather the other servers keep running if one of the servers in my group fails.  I have seen cluster diagrams with more then one SAN – are those extra SANs backups?  Seems like you have to have a fail-over SAN or you are at risk.

    3)      Anyone know of a supplier for building a SAN?  How about SANs for reasonable prices?  I would like to build my own cluster to play around with but on my budget it would need to be pretty cheap (~$800).  I have all the software from my MSDN subscription, so that’s not a problem, and I have lots of computers I play around with.  I did find this:

    http://searchstorage.techtarget.com/infoCenter/askTheExpertsAnswer/0,294272,sid5_gci929562_tax294583,00.html

     

    but a lot of it is over my head.  For example: I don’t know what a “drive shelf” is and Google didn’t help much there.  Also, do you have to use fiber?  He starts off saying you can use SCSI but then says you need fiber.  I was on a project about 4 years ago when our IT guy was setting up a SAN and we found that it was slower then our desktops when we ran tests.  We found out the fiber was slower then SCSI but it had more bandwidth – in other words:  fiber is a bigger pipe then SCSI but a slower one.  Is that still true?  If so I think SCSI is the way to go unless you know your cluster is going to get a lot of simultaneous client hits – which is not the case if your users are normally going through a web site or a middle tier to hit your DB.

     

    Thank you for your time,

    Ted

  • October 19, 2005 at 4:09 pm

    #598513

    Check out the following links for a start ...

    http://www.emc.com/

    http://www.hds.com/pdf/wp_149_san_nas_convergence.pdf

     

    By the way a SAN is not a cheap venture ... a 1 cabinet Hitachi with a few terrabytes of storage will cost roughly 1/2 million dollars. Each empty cabinet after that is about 1/4 million dollars (empty - to fill it with disks another 100k). Then there are switches (usually 2 for redundancy), fiber cabeling, dual HBA (host bus adaptor) cards per server for fiber connectivity, not to mention service contracts and upgrades ....

    By the way a SAN is a just a super redundant box of disks made up of various RAID arrays. It is usually connected to a number of server via it's own fiber optic network.

    RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."

  • October 19, 2005 at 7:23 pm

    #598555

    Wow Rudy, those are some pricy toys!  You know Dell's SANs start at about $10k?  Also, if it is just a RAID box I dont see why you couldnt build one on the cheap, to play with.

  • October 24, 2005 at 9:49 am

    #599564

    Expensive yes. But what is the cost of replacing your data ? Everywhere I've worked in the last 15 years has imlpemented one or more SANs. EMC is the oldest vendor, Hitachi next and now from a gogled link, DELL.

    However, the 10K starting price is quite a bit of a come on I believe. 1 Q-Logic HBA adapter card is about 1k alone and the link below touts 2 per server ... it also includes redundant (2) fiber switches and fiber cabling ... all this for 10k ... I think not.

    http://www1.us.dell.com/content/topics/global.aspx/power/en/ps3q01_muirhead?c=us&cs=555&l=en&s=biz

    As for fiber switches, Brocade is the original/pioneer in this area. Cisco is now in the market place (we are using them presently) but there are a few issues (not as solid as Brocade). Now Dell is there too.

    RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."

  • October 24, 2005 at 12:39 pm

    #599627

    Rudy,

     

    I am not concerned with the price of replacing my data.  That is zero for my test environment.  I am concerned with creating a cheap SAN/cluster I can learn from.

  • October 27, 2005 at 9:37 pm

    #600795

    Try this out:

    http://www.sql-server-performance.com/installing_sql_clustering_virtual_server.asp

    You can create your cluster on some virtual machines; you don't need a SAN this way

     

  • October 28, 2005 at 2:45 pm

    #601101

    Ah!  Now we are getting somewhere.  Thanks for the tip!

Viewing 7 posts - 1 through 6 (of 6 total)

You must be logged in to reply to this topic. Login to reply