Linked server availability

  • Hi,
    
    
    Due to the enormous ammount of servers and databases I created a script to gather information using linked servers. 
    Every now and then one (or more) server(s) can be unavailable ( maintenace / reboot etc etc ) and my script will 
    end on an "not available" error.How can I script (TSQL) a check-mechanism
    "if linked servers is not responding -skip - else - run the rest " ??
    Please help me out on this.
    GKramer
    The Netherlands
  • You could do it that way:

    Start your day with pinging your servers first.

    Place all your linked servers in a table like below on a master server:

    Server_ID Server_Name     Status

    1             Server#1            Yes

    2             Server#2            Yes

    etc

    -Loop thru that table from min serverid to the max serverid using While.

    -Ping servers and store results in a temp table.

     Like:

         Set @cmd='ping ' + @servername

         INSERT INTO #t EXEC master.dbo.xp_cmdshell @cmd

    -Select only Errors  LIKE '%timed out%' or LIKE '%host unreachable%' from that temp table

     and insert them with the serverid (servername) into perm tab

    -Update your first table and set Status column to the appropriate values:

     Yes-If server is available

     No-If you can't reach it

    Run your other jobs based on status 'yes'

  • The solution posted is a good start, but I would not rely on ping alone ... The OS could be alive and SQL Server down is one sitiation I've seen in the past. Also, sometimes ICMP traffic (that carries ping) is disabled - an example is an internal SQL server and one in a DMZ - exposed to the internet. I prefer to use an OSQL command in liue of the ping and just have is perform SELECT @@SERVERNAME. This always works. You'll have to modify the SELECT for errors a bit but it's easy. Besides if you use the OSQL coommand you don't even need to PING !

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

  • Barsuk,

    Searching for a sollution I found the part you mentioned but putting it into a cursor checking a selection of our servers was a liitle more difficult due to the datatypes to be used.

    declare @servername sysname

    declare @Result int

    declare @String01 sysname

    DECLARE Auto_state CURSOR FAST_FORWARD FOR

    select servername

    from   tables

    open Auto_state

    fetch next from Auto_state into @servername

    while @@fetch_status = 0

    begin

       set @String01 = 'ping '+@servername

       --print @String01 

       exec @result = master..xp_cmdshell @String01 , NO_OUTPUT

       IF (@result  = 0)

          PRINT @servername +' is reachable'

       ELSE

          PRINT 'No ping possible to '+@servername

    fetch next from Auto_state into @servername

    end

    deallocate Auto_state

    Rudy,

    You are right not to rely on the ping alone. I will invoke you hints into my script.

    Thank you guys for helping me out.

     

     

  • What Rudy was saying above is the following:

    Declare all variables, encompass the code in stored procedure and run it as job regularly on your master server.

    The above code you can include in the same SP too.

    select @servername=min(servername) from YourMasterTable

    while @servername is not null

    Begin

    Set @cmd = 'osql -E -S ' +  @servername + ' -q "SELECT @@ServerName"'

     Exec @status = master..xp_cmdShell @cmd

    If (@Status = 0)

                   Print 'SQL Server is Live: ' + @servername

     Else

                   Insert this record into the table and retrieve it later for notification/analysys

    select @servername=min(servername) from  YourMasterTable where servername > @servername

    end

  • I run this....

    CREATE

    procedure usp_HelloServer

    @ServerName nvarchar(128)

    as

    declare @isql nvarchar(255),

    @rc int

    set @isql = 'osql -S' + rtrim(@ServerName) + ' -U<user> -P<password> -n -h-1 -I40 -Q"select @@version"'

    select @isql

    EXEC @rc = master..xp_cmdshell @isql, no_output

    return @rc

  • Barsuk,

    The part you where telling about (almost simulair)  has been invoked already and its even complexer now. (automated updating on some status fields and sending e-mails regarding (un)availebility ).

    Right now I'm dealing with some Foreign server authentication using the -E switch but one of the DA's is looking why this occurs.

    Glynne,

    set @isql = 'osql -S' + rtrim(@ServerName) + ' -U<user> -P<password> -n -h-1 -I40 -Q"select @@version"'

    is not such a good Idea.....-U<user> -P<password>  --> hard coding (your)(a) SA account with its PW ???

    Ever heard about SOX ( Sarbanes Oxley ) Better use the -E switch.

    Guus Kramer

    The Netherlands

     

  • If you aren't too far down the road of rolling your own, I've used a product called ServersAlive to good effect to monitor a pretty wide variety of servers, SQL and otherwise.  Nice feature set including monitoring, notification, corrective action (scripted), "expected results", disk space, etc.  All for not a lot of $, the "enterprise" version is a whole $239.

    URL is http://www.serversalive.com/ and no I'm not affiliated with them in any way, just like the product.

    Joe

     

  • Joe,

    For network and servermonitoring we use MOM. It's hugh, pretty fast, and enourmous flexible for all kind of monitoring of various platforms, applications and tools.

    The availability check will be for DBA purposes only because, as I mentioned before, many scripts run agains a lot of different servers ( approx. 240 ) on approx 800 database. Due to maintenace or reboot ( or if a server dies ) these scripts come to a halt and reports will be incomplete.

    And to be honest; Creating such a script is a challange !!

    Guus

  • We use MOM as well. However, MOM is only polling about once every 15-30 minutes (so you have a window when things could be down and you are not aware) . I've never had issues with the OSQL method. I execute it as a scheduled task every 5 minutes. The OSQL as step 1 and an second step to send me email if the first step fails only. As for the number of servers, well, if you add them as linked servers (as a part of the build process) maintenance is a non-issue. If you utilize an MSX server it's even easier for scheduling and maintenance.

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

  • I am thinking about getting Idera SQl Diag for certain servers. Nice tool, but on a busy server it looks like it creates some overhead ( by running server traces)

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