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SQL Server Forum / Other Technologies / Clustering / January 2005Veritas storage foundation HA for windows
Hi, We have been looking at Stratus and Marathon Technologies for High Availability solutions for SQL Server. Zero time is a requirement as well as not having to make our application "cluster-aware". Microsoft Clustering requires application modifications and almost 2 minutes of downtime for the failover to happen. There is a product out on the market called: "Veritas storage foundation HA for windows". Does this product allow for zero application down time and and no application rewrite? Is this an alternative to a Stratus box or a Marathon Technolgoes solution for HA? If someone could get back to me tonight it would be appreciated. Thanks, Todd Hi As soon as SQL Server has to be shut down and start up (used by all clustering / HA availability solutions), you need to re-connect. SQL Server 2005 will have database mirroring, resulting in the MDAC stack doing the re-direction to the new machine, with about 5 second downtime. Trying 100% uptime with an application that does not support it is really throwing money at a bad problem. What is your biggest worry? Hardware, OS or SQL server failure causing you downtime? Regards -------------------------------- Mike Epprecht, Microsoft SQL Server MVP Zurich, Switzerland IM: mike@epprecht.net MVP Program: http://www.microsoft.com/mvp Blog: http://www.msmvps.com/epprecht/ > Hi, > [quoted text clipped - 13 lines] > Thanks, > Todd Hi Mike, Thanks for the reply. We are mostly worried about HW failure. We do not have time to re-write the application and the down time has to be 0 (or almost zero). Has anyone used this product from Veritas. They claim "immediate" failover. I am looking to find out if someone could tell me how it works (i.e. is application re-write required and what is the down time for the failover). Thanks, Todd "Mike Epprecht (SQL MVP)" wrote: > Hi > [quoted text clipped - 43 lines] > > Thanks, > > Todd Hi Veritas "Storage Foundation" is a data solution. It includes Volume Manager, which is just a SAN LUN to OS Volume mapping driver (We use it at work). This is a solution to manage your data, not the services like SQL Server. To make an application cluster suitable ("cluster aware" is for used for software running on a cluster), you just need to have you error handler re-try a connection a number of times when the connection drops. A no-brainer if an application is written correctly. Most of the time that we have hardware failure, the failure causes corruption of data. RAID controllers go bad, write junk and even the best cluster is screwed. No matter what HA solution you use, you are still limited to what the weakest component can do to your system. Hope you have multiple generators, multiple UPS's, multiple switches, multiple SANs, multiple ...well of everything. Whatever you use, test it for a good period of time. You might find that what you though was bullet proof has worse uptime than a single server. Regards -------------------------------- Mike Epprecht, Microsoft SQL Server MVP Zurich, Switzerland IM: mike@epprecht.net MVP Program: http://www.microsoft.com/mvp Blog: http://www.msmvps.com/epprecht/ > Hi Mike, > [quoted text clipped - 58 lines] > > > Thanks, > > > Todd Hi Mike, Thanks for the reply. How about Veritas Storage Foundation "HA" for Windows? Are you familar with this "HA" version? The datasheet claims "immediate" failover (see excerpt below: "If one of the servers or resources running on the server in a cluster becomes unavailable as a result of failure or maintenance, another server immediately begins providing service, a process known as failover." My question is with this HA version and/or any SQL server options that Veritas has... Does Veritas have an offering that does NOT require application re-write? And is the failover time going to be any quicker than Microsoft/SQL clustering? I am not sure what you get with Veritas that you don't get with basic Windows 2003/SQL clustering. Thanks, Todd "Mike Epprecht (SQL MVP)" wrote: > Hi > [quoted text clipped - 101 lines] > > > > Thanks, > > > > Todd Storage Foundation HA aka Veritas Cluster Server is in many ways comparable to MSCS. It is not instantaneous and I don't think anything really could be otherwise you'd have a huge risk of phantom failovers. There is always latency where the clustering technology has to decide that a fault has indeed occurred on a specific node and that the right course of action is to failover the affected resource(s) to another node. In terms of application rewrite, when the failover occurs, the connection to SQL server is broken. This will always happen because either SQL Server has to be stopped on the primary (or it fails completely) and be brought up on the secondary node. This will always necessitate reconnecting to SQL Server and resubmitting your batch. In this way Veritas is no different to MSCS. The Veritas solution supports Standard Editions of SQL + Windows (MSCS does not), it's a little more flexible in terms of HCL and it has IMHO a much nicer GUI and resource model. Having said that, in terms of clustering SQL Server, the SQL cluster setup is probably more straight forward and integrated on top of MSCS than Veritas HA but it's not really that tricky to setup on Veritas either. If there's no compelling reason to go to the enterprise level editions of SQL + Windows other than HA then Veritas can make sense with its support for Standard Editions. If you already use Storage Foundation aka Veritas Volume Manager then it's not a big leap to move to the HA edition. Horses for courses......  SignatureHTH Jasper Smith (SQL Server MVP) http://www.sqldbatips.com I support PASS - the definitive, global community for SQL Server professionals - http://www.sqlpass.org > Hi Mike, > [quoted text clipped - 132 lines] >> > > > Thanks, >> > > > Todd |
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