Re: Add new cluster and use existing LUN's?

I don't have access to the tool you mentioned but will research it (Dell/EMC
is correct by the way). I still have the fear of affecting performance on
both virtual servers by forcing them to share the same 4 disks because RAID
10 is not even bulletproof enough to gurantee a good speed if we are high on
the disk I/O side. I didn't want to semi-blindly make a decision to purchase
another cabinet and additional drives...hence why I came out here looking to
see if a few MVP's reccomended against it. I figured real world experience
may help me in the decision.

Like I told Rodney, I know testing is in store for us--a smoking gun for the
decision. All I have now are my own opinions and reservations and that isn't
enough to guide my decision to spend or not spend money.

Thanks for the advice.

"Geoff N. Hiten" wrote:

> Even a SAN has a maximum I/O capacity. Whether you are I/O bound on the
> disks in question will determine whether using the remaining space will
> impact your current system performance. Your SAN vendor (EMC from the hints
> you dropped) should have tools (likely for an additional fee) that can
> measure IO at the LUN/RAID set/disk level. You will definitely need that
> capability in order to measure the impact of your proposed change. A quick
> test would be to run a simulated SQL I/O load on the newly created LUNs
> while monitoring I/O performance at the SQL, OS, and SAN levels. Do the
> same without the load and see how much you can get away with.
>
> Personally, I prefer to use LUNS that map one-to-one to RAID Sets, mostly to
> avoid this problem. Since that isn't a real option now, you may want to
> consider purchasing an additional drive tray. It isn't the cheapest
> solution, but it may be the most effective.
>
> BTW, you can share a LUN with more than one server. That is how a cluster
> is built. Access Logix whines about it but you can force it to do what you
> need. .
>
> --
> Geoff N. Hiten
> Senior Database Administrator
> Microsoft SQL Server MVP
>
>
> "skyline" <skyline@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:DA48AC82-6A9F-4738-BDB6-08D10D16EAB4@xxxxxxxxxxxxxxxx
> > The SAN is indeed capable. Creating a LUN out of the 225 GB of
> > unformatted
> > data and assigning it to the new SQL server storage group is quick and
> > easy.
> > The first 5 drives of our SAN share the system binaries, Snapview reserved
> > LUN's, and 3 additional LUN's all set as RAID 5 (making a total of 509 GB
> > divided between several different LUN's.) It is possible to share the
> > same
> > drives with more than one server, however you can't share one LUN with
> > more
> > than 1 server.
> >
> > However we would have 1 virtual server accessing the original LUN of 175
> > GB
> > and the other virtual server accessing the newly created LUN of 225 GB--my
> > only hang up being the fact that the 2 LUN's exist on the same set of 4
> > drives and if you have 2 completely independent SQL servers accessing the
> > same drives is it going to put a hurt on performance. Again, t-logs stay
> > seperate (IE the 2 virtual servers would not be sharing the t-log drives,
> > they would each have their seperate set of RAID 10 drives) so that is my
> > only
> > saving grace thinking this implementation may be possible.
> >
> > I am here because I need a second opinion (and 3rd or 4ths if possible)
> > from
> > some higher SQL guru's. I personally am the Net Admin so my SQL
> > experience
> > is not broad however I understand the concept of the SAN well and know
> > what I
> > am looking to do with the SQL servers.
> >
> > Thanks!
> >
> > "Rodney R. Fournier [MVP]" wrote:
> >
> >> It depends on the SAN. You may not be allowed to share the drives with
> >> different servers.
> >>
> >> Cheers,
> >>
> >> Rod
> >>
> >> MVP - Windows Server - Clustering
> >> http://www.nw-america.com - Clustering Website
> >> http://msmvps.com/clustering - Blog
> >> http://www.clusterhelp.com - Cluster Training
> >>
> >> "skyline" <skyline@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> >> news:A4415101-D95B-4871-A666-4D4A2497275F@xxxxxxxxxxxxxxxx
> >> >I realize that testing is the ideal way to come to the complete
> >> >conclusion
> >> >on
> >> > our pathway but my first and foremost question really is has anyone
> >> > successfully used a set of drives and have 2 luns for 2 different
> >> > virtual
> >> > servers on that same set of drives?
> >> >
> >> > I'd like to know if I am doing something "average" or if the general
> >> > consensus is against such an idea. That helps me to determine how much
> >> > of
> >> > a
> >> > possibility this really becomes and how much money I will be spending.
> >> >
> >> > Thanks for your input thusfar.
> >> >
> >> > "Rodney R. Fournier [MVP]" wrote:
> >> >
> >> >> You need to stress test, look at the results, and then test some more.
> >> >> Testing will tell you what the correct answer is for your environment.
> >> >>
> >> >> Cheers,
> >> >>
> >> >> Rod
> >> >>
> >> >> MVP - Windows Server - Clustering
> >> >> http://www.nw-america.com - Clustering Website
> >> >> http://msmvps.com/clustering - Blog
> >> >> http://www.clusterhelp.com - Cluster Training
> >> >>
> >> >> "skyline" <skyline@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> >> >> news:18DB25CC-37FC-4FEF-AF56-64696BE9D0B8@xxxxxxxxxxxxxxxx
> >> >> > Hi All,
> >> >> >
> >> >> > We have a Win2003 Enterprise/SQL 2000 "active/passive" cluster, and
> >> >> > we
> >> >> > want
> >> >> > to split a few larger DB's off to a seperate and new
> >> >> > "active/passive"
> >> >> > cluster. The reason for the split is to allow this new cluster to
> >> >> > control
> >> >> > the one application and the other cluster to control the existing
> >> >> > app.
> >> >> > Currently we have:
> >> >> >
> >> >> > SQL LUN occupying 4 Raid 10 disks with 175 GB assigned to this LUN.
> >> >> > Doing
> >> >> > the math leaves us with appx. 225 GB left on these 4 discs that is
> >> >> > unnassigned and unformatted.
> >> >> >
> >> >> > T-log/Quorum LUN occupying 2 Raid 10 disks with all of the space
> >> >> > assigned
> >> >> > to
> >> >> > this LUN (appx 134 GB).
> >> >> >
> >> >> > We are most likely not going to utilize the entire 175 GB for the
> >> >> > data
> >> >> > collection side let alone the additional 225 GB. At what impact to
> >> >> > the
> >> >> > disk
> >> >> > I/O are we going to suffer if we create the new a/p cluster using a
> >> >> > newly
> >> >> > assigned LUN that occupies the previously unformatted 225 GB on the
> >> >> > SQL
> >> >> > data
> >> >> > disks? So essentially we would have 2 seperate virtual servers
> >> >> > operating
> >> >> > off
> >> >> > of the same spindles, however 2 different LUN's. My gut feeling
> >> >> > says
> >> >> > that
> >> >> > we
> >> >> > would take some type of I/O performance hit since 2 seperate high
> >> >> > I/O
> >> >> > applications are accessing the same spindles. We would however have
> >> >> > 2
> >> >> > new
> >> >> > RAID 10 disks for the t-logs and quorum of the new cluster and since
> >> >> > they
> >> >> > are
> >> >> > the highest I/O portion of SQL and would not be sharing this is the
> >> >> > only
> >> >> > reason I think the idea may be feasible.
> >> >> >
> >> >> > The reasons for trying to use the unformatted space on those 4
> >> >> > spindles
> >> >> > is:
> >> >> >
> >> >> > A) The data collection app already running on those spindles in the
> >> >> > 175
> >> >> > GB
> >> >> > space is never going to use all of that space (it is using 50 GB
> >> >> > currently
> >> >> > and at least half of that is the other app we want to split off).
> >> >> > So a
> >> >> > future of adding the 225 GB as a metalun to the existing SQL LUN is
> >> >> > slim
> >> >> > to
> >> >> > nill.
> >> >> >
> >> >> > B) We are hosed on that 225 GB of space for eternity really. If we
> >> >> > can't
> >> >> > use it for another SQL cluster I don't think there is anyway we
> >> >> > would
> >> >> > use
> >> >> > it
> >> >> > for file storage for example. That is based on my opinion...I have
> >> >> > a
> >> >> > hard
> >> >> > time believing it is okay to add another set of SQL data let alone
> >> >> > file
> >> >> > data.
> >> >> >
> >> >> > C) We only have 3 slots left in the first SAN cabinet. We will be
> >> >> > using 2
> >> >> > of those for a RAID 10 t-log setup for the new SQL cluster so that
> >> >> > leaves
> >> >> > us
> >> >> > with 1 drive space open for the new SQL cluster data
> >> >> > which=impossible.
> >> >> > So
> >> >> > now we not only have to buy additional drives but also a new cabinet
> >> >> > and
> >> >> > all
> >> >> > associated hardware.
> >> >> >
> >> >> > Keep in mind our main goal here is the processing power. Our
> >> >> > existing
> >> >> > cluster's processor is by no means outdated, but the data collection
> >> >> > AND
> >> >> > reporting runs at the same time are causing slow downs due to
> >> >> > processing
> >> >> > requests from many different applications. If reporting were on
> >> >> > it's
> >> >> > own
> >> >> > cluster that means it has its own server to beat up on and our
> >> >> > clients
> >> >> > don't
> >> >> > notice delays in web surveys or IVR calls when the daily reports are
> >> >> > being
> >> >> > aggregated.
> >> >> >
> >> >> > Any help provided is greatly appreciated.
> >> >>
> >> >>
> >> >>
> >>
> >>
> >>
>
>
>
.

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