Re: Clustering for Performance
- From: "Z" <z@xxxxx>
- Date: Wed, 11 Jan 2006 14:43:26 -0600
Oracle RAC, while it provide lad balancing, doesn't automatically give you
improved performance or scalability. With RAC, you have multiple servers
all pointing at a single database. So, 100% of the reads and write still go
to the same disk device. That means when you saturate the disk I/O, you
acually lose performance and scalability. Your transactions also take
longer than they would if it was a single Oracle server, because when you
plug in an architecture like that, you have to employ technology that
arbitrates every write action to ensure that more than one user isn't
changing the same piece of data at the same time and if they do, having a
way to figure out "which one wins".
Oracle RAC looks really good on paper and it's a really good marketing ploy.
Implementing it in the real world is the same as implementing any
distributed data architecture where you could possible write to multiple
nodes at the same time. There isn't any technology that magically takes
care of any of the issues.
"Richard" <Richard@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:427BB31F-57CA-43A9-965C-E5F18196D696@xxxxxxxxxxxxxxxx
> Thank you Geoff and Andrew for you swift responses.
>
> We are actually looking for a consultant to come in and help with this.
> However I am just doing some ground work beforehand.
>
> I was hoping that SQL Server 2005 would give us some performance
> improvements (such as true Load Balancing like Oracle Real Application
> Clusters), but the improvements over 2000 seem to be mostly for failover
> rather than scaling.
>
> Thanks again for your input
>
> Richard
>
> "Andrew J. Kelly" wrote:
>
>> Richard,
>>
>> Try not to take this the wrong way but if you are asking questions like
>> these and need to implement a system that large you are probably a bit
>> over
>> your head. I suggest you seriously consider hiring a consultant who has
>> been thru things like this before. Quite honestly there aren't many
>> people
>> who have dealt with systems that large. And if not done correctly it will
>> almost certainly turn belly up and die when you even get close to that
>> many
>> users. That said here are a few comments. One is I doubt you will really
>> have 40K concurrent users especially since SQL Server only allows
>> 32,767<g>.
>> Even with heavy use web based apps you rarely have as many concurrent
>> connections as you would think. And if you are talking anywhere near
>> this
>> amount you are talking some serious hardware to support it. As I
>> mentioned
>> in another post Clustering is not a load balancing option. Only one node
>> at
>> a time has control over a specific disk resource in the cluster. So even
>> with Active / Active (or more correctly Multi-Instance) you can't share a
>> database since it resides on only one disk resource. You can't design a
>> system like this in a newsgroup and if you try you will fail. It
>> requires a
>> very careful and well laid out plan to implement a large scale database
>> application.
>>
>> --
>> Andrew J. Kelly SQL MVP
>>
>>
>> "Richard" <Richard@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
>> news:A115E5ED-8801-4142-B921-FD25665FE3C0@xxxxxxxxxxxxxxxx
>> > Hello All. I need to set up quite a large SQL System 2005 system that
>> > needs
>> > to deal with 40,000 concurrent users, and one of the tables will
>> > contain
>> > blob
>> > data. 40,000 users throwing around Mb's of data at the same time
>> > worries
>> > me a
>> > little bit!
>> >
>> > My question is to do with Database Clustering and Mirroring. From what
>> > I
>> > can
>> > see, there is still no load-balancing with SQL Server 2005, so does
>> > this
>> > mean
>> > even in a clustered environment I am still basically only using a
>> > single
>> > database server? I have seen many posts that tell me that clustering is
>> > ONLY
>> > for failover and not for performance. I understand that with
>> > Active/Passive
>> > this is the case, but how about Active/Active? If I can set up
>> > Active/Active
>> > (2 nodes? 4 nodes? 8 nodes? how many are possible?) with a SAN and NOT
>> > have
>> > failover implemented (can I turn failover off?) then would I have a
>> > load
>> > balanced environment? I could then have all nodes running up to 100%
>> > (because
>> > I don't have to worry about the failover) and therefore give me a
>> > dramatic
>> > increase in performance compared with using a single server?
>> >
>> > If I can do this then I can set up 2 identical clusters and an extra
>> > server
>> > for the witness, and use database mirroring for failover? Of course I
>> > understand that mirroring will decrease performance on the clusters.
>> > But
>> > would this give me a super-fast database system that might cope with
>> > what
>> > I
>> > need?
>> >
>> > Also, I am thinking about taking the blob data of of the database and
>> > create
>> > a new database that just deals with the blobs. How would this affect my
>> > clustered/mirrored environment?
>> >
>> > Thanks
>> >
>> > Richard
>>
>>
>>
.
- References:
- Re: Clustering for Performance
- From: Andrew J. Kelly
- Re: Clustering for Performance
- From: Richard
- Re: Clustering for Performance
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