Archive for May, 2010
An Active Manager operation failed. Error: Operation failed with message: MapiExceptionNotFound: Unable to mount database. (hr=0x8004010f, ec=-2147221233)
Posted by Brajesh Panda on May 26, 2010
Posted by Brajesh Panda on May 12, 2010
This is a obvious question always asked by my customers; Do we need single DAG or Multiple DAG?
Answer differs as per the requirement –
1. If all mailbox servers are located in same site, there is no good justification having multiple DAGs; this is going to limit number of members; hence copies too. Because each Mailbox server can be part of one DAG.
2. Let suppose customer is stretching the DAG between sites for site level redundancy; Number of DAGs depends on how many sites going to host active mailbox databases. If both sites or multiple sites going to have active databases we are going to need multiple DAGs stretching across sites. Because if you consider one DAG with multiple active databases in different sites, WAN failure is going to bring down those remote site databases which don’t have Quorum. So better to have multiple DAG with quorum in each site.
Posted by Brajesh Panda on May 11, 2010
In my previous article we discussed about 3 Node (ODD Member) DAG (2 in primary site & 1 in secondary site) along with Node Set Majority & File Share Witness Quorum Model.
In this article lets talk about EVEN number based stretched DAG & which has more than 2 member nodes of DAG. So lets consider 4 Node based DAG. Where Primary & Secondary site has 2 nodes each. As this model is based on even number we can’t consider Node Set Majority Quorum. We have to consider a extra vote in quorum model. As DAG concept is based on shared nothing architecture, Disk based Quorum goes out of consideration, so we have to use File Share Based Witness.
If active mailbox databases are only in primary site, we can include all these 4 nodes into a single DAG and create 3 Data Base Copies; Keeping one copy at secondary site for failover.
But in case both sites are going to have active mailboxes we will be needing TWO Stretch DAG between sites with two different file share witness. Well it can be created using 1 node from each site with a file share witness at the primary site. But by doing this we will only have 2 Database Copies & each failure will be resulted as site fail over. So better to increase number of nodes in each site to at least 3 ; DAG1= 2 Node from Primary + 1 Node from Secondary, DAG2= 2 Node from Secondary + 1 Node from Primary. Fail-over & fail-back process for these DAGs will be equal to 1st scenario we discussed in previous article.
If our Active Directory site is streched then we have to use a single CAS Array FQDN for both side CAS servers but it may generate cross site MAPI traffics & complex load balancing issues. But if we have two different AD Sites we can have two different CAS Array Objects in two different site & users in that site can use the same for Outlook connectivity. While using two Active\Active sites better to use two different namespace for client access.
Posted by Brajesh Panda on May 8, 2010
Mr. Gil Kirkpatrick got a nice article about Windows 2008 AD backup & restore 😉
Posted by Brajesh Panda on May 7, 2010
Nice Blog about two good iSCSI Storage Box!
Posted by Brajesh Panda on May 6, 2010
This is a nice article by Graham on Equal Logic. I really like the whole story 😉