Polybase

  • I am trying to configure polybase scale out, what ports do you recommend? Is it 16450 -16460?

    The service account so there are 2 services for Polybase might not want all 4 services i.e. database, sql agent and polybase using the same id. Scale-out option need Domain account and can share a MSA account for all 3 servers?  Please advice! Thanks in Advance!

  • Thanks for posting your issue and hopefully someone will answer soon.

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  • I can't speak for the scale out part, but for the rest, I think it really depends.

    For the ports, I recommend any that are not in use and that your IT dept allows to be opened in the firewalls and that are preferably not in any reserved port lists.  Default ports are likely going to be fine unless you have some need to change them.

    As for the service accounts, which accounts can you live with if they get disabled?  If you have one account per service, then if one gets locked out, you only lose new things that service may do.  If all of them are the same account, you lose all of them.  Where I work, we don't follow best practice with the accounts and it is one SQL account for all live SQL stuff (SSRS, SSIS, SQL Agent, and SQL Instance).  The advantage is it is a single account we need to manage in AD.  Downside is if it gets locked out, it locks it out on ALL of those services.  For SQL Instance we've never had any issues, but the SQL Agent will fail to start new jobs.  Offhand, I am not certain if Polybase needs to spawn anything new once it is running so it may not be impacted by a locked account.

    If you want scale out, I am pretty sure you would want them to all have the same account.  That way the permissions can be set up identically on all of the servers and it makes it nice and easy.  Otherwise permissions are going to be painful to set up for each instance of it.  But I'd check the official docs from MS to find that information out.

  • Thanks! However, I am having the problem to not able to start the Polybase services. I also checked to make sure the tcp/IP is also enabled. There is no firewalls. Any thoughts?

  • What do the logs say?  They will very likely tell you exactly why it can't start the service.

    Without seeing any logs, my first thought is permissions.  Does the Polybase service account have all of the access it requires?  If you don't know what access it requires, check the Microsoft Documentation as it will let you know and you can make sure that the account you gave the Polybase service has the appropriate permissions.

    It is HIGHLY unlikely that a misconfigured firewall would stop the service from starting, but if the ports are already in use, that could cause it to fail to start too.

    BUT my VERY first place that I'd check is the logs.  Logs will tell you why it failed to start and sometimes even tell you what you should do about it.

  • a few things to check if polybase is not able to start;

     

    on my developer edition box, I had to make sure TCPIP connections were enabled, which is not an issue on a server version, but if you were testing, it's not enabled by default

    the services for polybase MUST be a windows or domain account.

    https://social.msdn.microsoft.com/Forums/security/en-US/f3b7473c-fde9-4e6c-ad53-108e9de768dc/polybase-services-wont-start-up?forum=SQLServer2016Preview

    Lowell


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  • This what the error I am getting.

    A timeout was reached (30000 milliseconds) while waiting for the SQL Server PolyBase Engine (MSSQLSERVER) service to connect.

    I changed the startup time to delayed start but it did not help.

    Would this be a solution?

    https://support.plesk.com/hc/en-us/articles/115000839045-After-server-reboot-services-can-not-be-started-A-timeout-was-reached-30000-milliseconds-

  • I tried the registry no luck.

  • The error you listed to me looks like an error from Windows service manager (or SQL Server Configuration Manager), not from Polybase.  I would check the log files and/or windows event log as those are going to give you better results than the service log popup window which doesn't have a lot of options for error messages it can present to you.

  • Thanks. After uninstall/reinstall has resolved the issue. Scale out group is configured on availability group between 2 nodes. Node 1 and Node2 are part of HA. So now node1 is head and node 2 is compute. The question is when node2 becomes primary how does scale out group play the role during failover. Any thoughts?

  • Any thoughts?

  • Not from me.  I've never configured scale out for Polybase, or anything for that matter.  My systems are pretty lightweight and I've not had a need for it.

    My advice - test it out on your test environment.  Experiment and see what happens.  Even if we tell you one thing and you have a configuration option we didn't expect and forgot to ask about, you MAY have a different experience than what we tell you.

    When implementing anything new it is ALWAYS best to put it on a test environment and test it out to make sure it works the way you expect.  Have you tested that node1 is the head and that node2 is compute?  Does that work the way you expect?

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