SQL Server disk sub-system (overhaul) performance questions

Collapse
This topic is closed.
X
X
 
  • Time
  • Show
Clear All
new posts
  • ajjvn

    SQL Server disk sub-system (overhaul) performance questions

    I 'inherited' a group of SQL Server server class machines. They are
    true server technology but the disk sub-systems are lacking. There is
    one hot-swap backplane that all the drives share (with one SCSI
    channel) thusly even though there are three logical drives (composed
    from 6 to 8 hard drives), they all go through one channel. This is
    creating a performance issue that is noticable and can be seen in
    various performance counters that Microsoft recommended one should
    monitor in terms of disk I/O. For a cheaper 'fix', I can add a
    seperate two drive bay (with its own SCSI channel) with mirrored
    drives. I would then mostly likely place the transaction log files on
    this new channel. Or I could place the indices filegroup files on
    this new channel for DBs with mainly searching going on (not much
    updating). If I went this route I would be leaning towards the
    transaction log move since the second method would require me moving
    DBs around quite a bit. Any input on this solution (besides spending
    more money)?

    What I would prefer to do is get a better server class machine or add
    an external drive bay solution (not a SAN). I would try to get three
    or four SCSI channels in the new hardware to split the different
    file/filegroups out (i.e. transaction logs files, data filegroup,
    indices filegroup, etc.). My only concern here is: would this more
    expensive solution be worth the money? As far as replacing servers, I
    have only two kinds of experience...re placing somewhat underpowered
    servers with slightly less underpowered servers and replacing overkill
    servers with even more overkill servers. In both cases, the disk
    sub-systems were fairly equivalent from the old system to the new one.

    Will going the three/four channel route really get data moving along?
    We have one server in particular that hosts a database (one of many on
    it) for a web application that gets decent traffic (it is a private
    login based system for internal use and external use by our clients'
    agents). Periodically throughout the day, there are 2-5 minute bursts
    where performance slows to a crawl. I want to spend more time
    profiling queries and such before recommending we spend more money,
    but the folks I am working for want quick results and there is quite a
    bit of stored procedure logic to profile and investigate. I know the
    disk sub-system is definately in need of an overhaul, but I would like
    to get an idea of peformance gains from adding either one additional
    channel over the existing single channel as well as going the
    three/four channel route over the existing single channel setup.

    Any information would be greatly appreciated.

    Regards,
    Tony
  • Erland Sommarskog

    #2
    Re: SQL Server disk sub-system (overhaul) performance questions

    ajjvn (ajjvn@hotmail. com) writes:[color=blue]
    > Will going the three/four channel route really get data moving along?
    > We have one server in particular that hosts a database (one of many on
    > it) for a web application that gets decent traffic (it is a private
    > login based system for internal use and external use by our clients'
    > agents). Periodically throughout the day, there are 2-5 minute bursts
    > where performance slows to a crawl. I want to spend more time
    > profiling queries and such before recommending we spend more money,
    > but the folks I am working for want quick results and there is quite a
    > bit of stored procedure logic to profile and investigate. I know the
    > disk sub-system is definately in need of an overhaul, but I would like
    > to get an idea of peformance gains from adding either one additional
    > channel over the existing single channel as well as going the
    > three/four channel route over the existing single channel setup.[/color]

    I don't have much experience of dimensioning servers, but from what you
    say it seems that upgrading the hardware is going to improve the system,
    but the performance problems with remain. Whlie better hardware can
    make some performance issues negligible, there are many ways to make
    a database engine so slow, that no hardware in the world can save it.

    So I predict that even if you buy all those disks, you will eventually
    be asked to analyse the application and look for ways to improve it.

    --
    Erland Sommarskog, SQL Server MVP, sommar@algonet. se

    Books Online for SQL Server SP3 at
    SQL Server 2025 redefines what's possible for enterprise data. With developer-first features and integration with analytics and AI models, SQL Server 2025 accelerates AI innovation using the data you already have.

    Comment

    • ajjvn

      #3
      Re: SQL Server disk sub-system (overhaul) performance questions

      What you say is true. We are doing a lot of profiling and analyzing
      but we know a server replacement will be in order down the road to
      handle a known increase in load. What we are wondering is if we move
      the hardware replacement sooner, how much will we benefit from it
      (based on others observations of somewhat similar changes in
      hardware).

      Anyone?

      TIA,
      Tony

      --------------

      Erland Sommarskog <sommar@algonet .se> wrote in message news:<Xns944C37 4BD9C5Yazorman@ 127.0.0.1>...[color=blue]
      > ajjvn (ajjvn@hotmail. com) writes:[color=green]
      > > Will going the three/four channel route really get data moving along?
      > > We have one server in particular that hosts a database (one of many on
      > > it) for a web application that gets decent traffic (it is a private
      > > login based system for internal use and external use by our clients'
      > > agents). Periodically throughout the day, there are 2-5 minute bursts
      > > where performance slows to a crawl. I want to spend more time
      > > profiling queries and such before recommending we spend more money,
      > > but the folks I am working for want quick results and there is quite a
      > > bit of stored procedure logic to profile and investigate. I know the
      > > disk sub-system is definately in need of an overhaul, but I would like
      > > to get an idea of peformance gains from adding either one additional
      > > channel over the existing single channel as well as going the
      > > three/four channel route over the existing single channel setup.[/color]
      >
      > I don't have much experience of dimensioning servers, but from what you
      > say it seems that upgrading the hardware is going to improve the system,
      > but the performance problems with remain. Whlie better hardware can
      > make some performance issues negligible, there are many ways to make
      > a database engine so slow, that no hardware in the world can save it.
      >
      > So I predict that even if you buy all those disks, you will eventually
      > be asked to analyse the application and look for ways to improve it.[/color]

      Comment

      Working...