No, your situation isn’t really that different because of the odd number of servers. MSFT says that you should keep the FSW local to the primary datacenter for the DAG, and use an alternate FSW for the secondary datacenter. Also, you’ll want to enable DAC mode - http://technet.microsoft.com/en-us/library/dd979790.aspx
Missy From: Sobey, Richard A [mailto:r.so...@imperial.ac.uk] Sent: Thursday, October 27, 2011 10:54 AM To: MS-Exchange Admin Issues Subject: RE: DAG Question I’m having real trouble getting my head around this. I’ve implemented – and tested – our DAG and it seems to work exactly as I want it to. *3 nodes in each datacentre (10Gig link between them; call them DC1 and DC2) * FSW in a third DC (another 10Gig link; DC3) When I was testing this, we cut off all the Exchange servers in DC1 from the network. DC2 mounted its databases fine. When we brought DC1 “back online” they didn’t try to mount themselves again (which is what I believe split brain to be). Is my situation quite different to the original poster’s, where I’ve got an odd number of nodes in each datacentre? I’m really curious about “misconception number 3” from Philip’s link below, as it makes no mention of a witness server being available. What if the DC with no connectivity to the primary site did have connectivity to the site where the witness server is, for example?) Sorry – I know this all sounds really dumb ☺ Richard From: bounce-9451031-8066...@lyris.sunbelt-software.com<mailto:bounce-9451031-8066...@lyris.sunbelt-software.com> [mailto:bounce-9451031-8066...@lyris.sunbelt-software.com]<mailto:[mailto:bounce-9451031-8066...@lyris.sunbelt-software.com]> On Behalf Of Young, Philip Sent: 27 October 2011 14:57 To: MS-Exchange Admin Issues Subject: RE: DAG Question Thanks Peter, found the Tech Ed 2010 presentation for this ... useful info. Also found another link that described the exact scenario of 3rd datacenter and why not to do it here http://blogs.technet.com/b/exchange/archive/2011/05/31/exchange-2010-high-availability-misconceptions-addressed.aspx Thanks all I believe I now have all I need. Regards Phil ________________________________________ From: Peter Johnson [mailto:peter.john...@peterstow.com] Sent: 27 October 2011 07:48 To: MS-Exchange Admin Issues Subject: RE: DAG Question Hi Philip If you can find it online check out Scott Schnoll’s “Mailbox High Availability in Exchange 2010” deep dive. It explains it really well. The issue with a single DAG solution in this scenario is as someone mentioned “split brain”. Regards Peter Johnson I.T Architect United Kingdom: +44 1285 658542 South Africa: +27 11 252 1100 Swaziland: +268 2442 7000 Fax:+27 11 974 7130 Mobile: +2783 306 0019 peter.john...@peterstow.com<mailto:peter.john...@peterstow.com> www.peterstow.com<http://www.peterstow.com> This email message (including attachments) contains information which may be confidential and/or legally privileged. Unless you are the intended recipient, you may not use, copy or disclose to anyone the message or any information contained in the message or from any attachments that were sent with this email, and If you have received this email message in error, please advise the sender by email, and delete the message. Unauthorised disclosure and/or use of information contained in this email may result in civil and criminal liability. Everything in this e-mail and attachments relating to the official business of Peterstow Aquapower is proprietary to the company. Caution should be observed in placing any reliance upon any information contained in this e-mail, which is not intended to be a representation or inducement to make any decision in relation to Peterstow Aquapower. Any decision taken based on the information provided in this e-mail, should only be made after consultation with appropriate legal, regulatory, tax, technical, business, investment, financial, and accounting advisors. Neither the sender of the e-mail, nor Peterstow Aquapower shall be liable to any party for any direct, indirect or consequential damages, including, without limitation, loss of profit, interruption of business or loss of information, data or software or otherwise. The e-mail address of the sender may not be used, copied, sold, disclosed or incorporated into any database or mailing list for spamming and/or other marketing purposes without the prior consent of Peterstow Aquapower. No warranties are created or implied that an employee of Peterstow Aquapower and/or a contractor of Peterstow Aquapower is authorised to create and send this e-mail. From: Michael B. Smith [mailto:mich...@smithcons.com] Sent: 26 October 2011 08:26 PM To: MS-Exchange Admin Issues Subject: RE: DAG Question The question doesn’t compute. ☺ The issue, as I believe another poster pointed out, is that reaching quorum is impossible with an even number of live servers that don’t have access to the FSW. The cluster will go offline. Warning: I don’t know your design goals. Based on what little information I have, I would tend to suggest you have two DAGs, keeping the same server distribution. Site A has two servers for DAG-1, site B has two servers for DAG-1, the FSW for site A is in site A. Reverse that for DAG-2 being homed in site B. Regards, Michael B. Smith Consultant and Exchange MVP http://TheEssentialExchange.com From: Young, Philip [mailto:philip.yo...@covance.com] Sent: Wednesday, October 26, 2011 10:41 AM To: MS-Exchange Admin Issues Subject: RE: DAG Question Ok thanks Michael. One reason for posting my question was that I could not find anyone else who had done it this way. I was told the reasoning behind this is that if even if we lost site A we would still have the 3 members in site B plus the fsw in Site C. is that logic flawed? Can you be more specific about what quorum issues we might face? BTW the intention is to have active mailboxes in both sites A and B. we are at the design/test phase so not written in stone yet. Regards Phil ________________________________________ From: Michael B. Smith [mailto:mich...@smithcons.com] Sent: 26 October 2011 14:48 To: MS-Exchange Admin Issues Subject: RE: DAG Question Yes. That could lead you to having quorum issues. Regards, Michael B. Smith Consultant and Exchange MVP http://TheEssentialExchange.com From: Young, Philip [mailto:philip.yo...@covance.com] Sent: Wednesday, October 26, 2011 9:37 AM To: MS-Exchange Admin Issues Subject: DAG Question We are planning an Exchange 2010 rollout and plan an 8-node DAG with 4 members in Site A and 4 in Site B and the FSW in Site C. Are there any drawbacks with doing it this way? Anybody have any good reasons why we shouldn’t do this? Thanks in advance. Regards Phil --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist ----------------------------------------------------- Confidentiality Notice: This e-mail transmission may contain confidential or legally privileged information that is intended only for the individual or entity named in the e-mail address. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution, or reliance upon the contents of this e-mail is strictly prohibited. If you have received this e-mail transmission in error, please reply to the sender, so that we can arrange for proper delivery, and then please delete the message from your inbox. Thank you. --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com with the body: unsubscribe exchangelist
