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  1. #1
    Join Date
    Dec 2002
    Location
    Antwerp, Belgium
    Posts
    227

    Question Unanswered: using a raid controler with cache

    Hi,

    I would like to know from you all what you think of using controler with 128 MB cache (PERC3/DI in a Dell PowerEdge 2650). There would be a lot of reading and writing in the database. What I found so far on the internet is mostly that cache for writing is not such a good solution. What do think?
    Johan

  2. #2
    Join Date
    Aug 2002
    Location
    Scotland
    Posts
    1,578
    May refer this link.
    --Satya SKJ
    Microsoft SQL Server MVP
    [IMG]http://sqlserver-qa.net/google_bart.gif[/IMG]

  3. #3
    Join Date
    Jan 2003
    Location
    Nottinghamshire, UK
    Posts
    364
    I'd Prob go for raid 5 like this

    C:\ Drive for OS
    D:\ For Raid ARRAY (3-5 disks or more) for Data Files .MDF (Random Access Fast Read/Write)
    E:\ Drive Single Drive for the Transaction LOG Files .LDF (Contiguos read/write)

    SQL Does so much in RAM cache - Make sure U got a few GIG

    Looks like a decent controller

    GW
    "Everything should be made as simple as possible, but not simpler." - Albert Einstein
    "Everything should be made as complex as possible, so I look Cleverer." - Application Developer

  4. #4
    Join Date
    Dec 2002
    Location
    Antwerp, Belgium
    Posts
    227
    thanks so far, but what I would like to know is: is there an advantage to using the cache of the controler when I need to perform lots of updates and inserts. And what happens in case of a long power failure ... Is my database still consistent or not?
    Maybe this is a straight forward issue for a lot of you, but I could use all the information that you might know of.
    Johan

  5. #5
    Join Date
    Jun 2003
    Location
    Canada
    Posts
    3
    Originally posted by jora
    And what happens in case of a long power failure ... Is my database still consistent or not?
    I would suggest that if you expect power failiures/spikes, Obtain a Uninteruptable Power Supply. Even if you don't expect them, it's still a good idea. Personally speaking, I would consider it as an essential item if you have mission critical data that has to remain consistent.

    A UPS would allow you to clear the cacheand then gracefully shut down the server and thus keep consistency errors at a minimum. Simple precautions often save lenghty(and costly) downtimes and/or data corruption.

    If there's data waiting to be written at the time of a power failiure and no UPS present then there might be data reliability issues if you're using the cache or not. You'd just have to hope that lady luck was on your side. Invest in a UPS. Don't leave luck to care for your data.

  6. #6
    Join Date
    Jun 2003
    Location
    Canada
    Posts
    3
    Originally posted by jora
    And what happens in case of a long power failure ... Is my database still consistent or not?
    To answer your question,
    It depends on what measures you take to ensure the safety of your server. If you do or don't use cache and the server's power fails you may find consistency errors although the severity can vary.

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