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2 Node DAG Disk Design

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2 Node DAG Disk Design - 3.Feb.2012 3:39:07 AM   
backdoor

 

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Hi @ all

I want to ask about your recommendation for the Disk desing in a 2 Node DAG.
I'm moving from Ex2003 to Ex2010 with the follow design

2 x HUB/CAS
2 X MBX with DAG

Now I'm thinking about this topic
The 2 MBX Servers have (at this time) 8 Disks
2 Disks are for the OS, so there are 6 disks left for the DB's an the Logs
How schould I configurate this disks?
my first thoughts were to use one disk for one DB and the logs; the second disk for teh second DB and the logs ....and so on.
than I read that this is so not recommended (not until you use 3 DAG Nodes)

so what should I do?
should I build up any Raid's? (maybe a Raid 1 with two disks)
If it is possible, I want to use at least 5 DB's (4 x Mailbox; 1 x Public Folder)

Have you any suggestions??
Post #: 1
RE: 2 Node DAG Disk Design - 3.Feb.2012 4:01:23 AM   
zbnet

 

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Did you use the Exchange 2010 Mailbox Server Role Requirements Calculator spreadsheet with all your user requirements to arrive at your server and storage design?  If not, what does it say about the best fit for your requirements?

http://blogs.technet.com/b/exchange/archive/2010/01/22/updates-to-the-exchange-2010-mailbox-server-role-requirements-calculator.aspx

Any strong reasons why you've chosen to seperate out the CAS/HT from the MBX servers?  For many, many scenarios MS are now recommending you deploy multi-role servers - http://technet.microsoft.com/en-us/library/dd298121.aspx gives you the situation.

(in reply to backdoor)
Post #: 2
RE: 2 Node DAG Disk Design - 3.Feb.2012 6:20:31 AM   
backdoor

 

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Hi zbnet

no, I didn't used the Calculator, because we are a small company and I thougt my planed design is totaly oversized
we have about 400 mailboxes with a max of 500MB, so normaly I would say that a single Server with multiple-roles is enough.
So my company want a HA solution an about 2 years ago I planned a HA solution. Part of this plan was the WNLB for the HUB/CAS server. As I understood it is not possible to install the WNLB and the DAG Cluster on the same box, isn't it??

That was my way to separate the roles ;-)

Now (since two weeks) we decided, to set up 2 Cisco Hardware Loadbalancer, but I didn't thought about to install all roles on one box (may this possible??)

just now I walked through the calculator (at least I tried it)
I'm not sure about the result
at the tap "Storage Design" the recommendation is

Optimal RAID Configuration: RAID-1/0
Optimal Number of Disks: 2

What did this mean?
One Raid 1/0 Disk for all Databases??
*confused*

< Message edited by backdoor -- 3.Feb.2012 6:22:22 AM >

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RE: 2 Node DAG Disk Design - 3.Feb.2012 6:44:44 AM   
zbnet

 

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400 mailboxes, each of maximum size 500MB (which is a bit small these days) gives you a theoretical maximum size of the database (excluding indexes, deleted items retention etc) of just 200GB - that's pretty small compared to the recommended maximum database size (in a DAG) of 2TB.  How big are your disks?

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Post #: 4
RE: 2 Node DAG Disk Design - 3.Feb.2012 7:18:19 AM   
backdoor

 

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one disk is 146 GB

Currently we have a 2 node active/passive Exchange 2003 Cluster
We have 7 DB's
they are 17; 15; 11; 9; 18; 6; 7 GB big

as you can see, a small company

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Post #: 5
RE: 2 Node DAG Disk Design - 3.Feb.2012 8:26:23 AM   
zbnet

 

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All your disks are 146GB?  Is this old kit?  For at least a year now 300GB disks has essentially been as cheap as the 146GB drives...

So, if you still want HA (small company with little spare cash for decent capacity hardware doesn't normally equate with HA requirements...), then you have basically two options:

1) 2 servers in a DAG; each with 8 disks - 2 for OS mirror; 6 for a RAID 1+0 438GB array, which should be large enough to accommodate logical volumes big enough for your (max) 400GB of mailbox storage and transaction logs so long as you don't set very large deleted item retention limits, or you don't need masses of transaction log overhead (so make sure your backups are reliable and regular).

2) steal one of the CAS/HT nodes to make a 3-node multi-role-server DAG and use the Cisco HLBs to balance the CAS array (this assumes the chassis of these servers is the same as the MBX models); as well as the 2-disk OS mirror in each DAG server, fit 4 disks as JBOD in each server; 2 logical volumes on each disk, one approx 40GB for the logs and one approx 100GB for the database (one per disk); and split your 400 users across the 4 disks/databases accordingly.

All of the above assumes you've speced the servers to be able to cope with the requirements of each configuration (procs, memory, NICs etc), but all the requirements for these are documented on TechNet, so make sure your solution is within spec before you implement in production.

(in reply to backdoor)
Post #: 6
RE: 2 Node DAG Disk Design - 3.Feb.2012 2:46:33 PM   
backdoor

 

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indeed, the hardware is round about 18 month old, but till now i wasn't be able to set the Servers up.
But now the time has come

as your post just #1 is an option, because the hardware of the HUB/CAS server are different.

just for my understanding

after I create the Raid bundle I create logical volumes
how many? for any DB one??
What about the log files?

i.e.

volume
d:\
DB1
Log

volume
e:\
DB1
Log

volume
f:\
DB1
Log

...........


5 volumes for the 5 mailbox DB's
1 volume for the PF DB

thx for your help :-)

(in reply to zbnet)
Post #: 7
RE: 2 Node DAG Disk Design - 6.Feb.2012 10:28:06 AM   
zbnet

 

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It is best practice (although not an absolute requirement in Exchange 2010) for recovery purposes to seperate logs from databases, placing them on different logical volumes based on seperate physical disks.

You don't have enough disks to do that for all your planned databases, though - this is what comes from buying the kit first, then designing the layout to fit it :-)

FYI, the details are here:

http://technet.microsoft.com/en-us/library/ee832792.aspx

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Post #: 8
RE: 2 Node DAG Disk Design - 7.Feb.2012 3:14:56 AM   
backdoor

 

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quote:

ORIGINAL: zbnet

It is best practice (although not an absolute requirement in Exchange 2010) for recovery purposes to seperate logs from databases, placing them on different logical volumes based on seperate physical disks.



yes I know, currently I have separate my logs from the DB

quote:


You don't have enough disks to do that for all your planned databases, though - this is what comes from buying the kit first, then designing the layout to fit it :-)


that's not completely right, I have an option to get 8 more disks in the box. But first of all I wanted to check out what is possible with my currently configuration.
If it isn't a good and safe config I have to try to get some more money to buy some more disks
I not design a Exchange Organisation every day, so I have to learn, that's why I'm asking :-)
so please, what would you do in my situation?
What configuration would you do?
Buy some more disks?
And how would you configure it?

(in reply to zbnet)
Post #: 9
RE: 2 Node DAG Disk Design - 7.Feb.2012 4:12:09 AM   
zbnet

 

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With the greatest respect, I cannot produce for you the most optimal design for your requirements.  You have not shared a full picture of your requirements, nor a full picture of your resources (for example, adding new disks to the servers only appeared as an option in your latest post).  I'm not saying that you necessarily need to document all this stuff on here, for I don't believe that would be appropriate.  The nature of internet forums means they are far better suited to answering fairly well-focused technical questions, and less well suited to full consultancy engagements, which take quite some time, and are worth paying for.

That's not to say I'm unwilling to help, but I think the extent of the help is pointing you to helpful Technet resources, the capabilities of the Mailbox Role Requirements Calculator spreadsheet, and answering your focused technical questions.  Beyond that, if you're still out of your depth, then maybe you do need to consider engaging a short-term consultant to design for you a suitable response to a requirements-gathering exercise.  Because without a full understanding of your requriements, I could design you *a* system, but it might not be the *right* system for your needs.

You may not need this level of input.  If you can decide how big your database LUNs need to be (and you need to RAID-1 or RAID-10 them if you only have 2 nodes in your DAG) and you can decide to seperate out your logs LUNs from your DB LUNs (see http://technet.microsoft.com/en-us/library/ee832794.aspx), then you're basically there, aren't you?

< Message edited by zbnet -- 7.Feb.2012 4:15:32 AM >

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Post #: 10
RE: 2 Node DAG Disk Design - 8.Feb.2012 2:58:16 AM   
backdoor

 

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I understand that you cannot give me an optimal design for my environment. No Problem
Just one more question
Is it possible (and supported) to do the follow design
From my 6 disks, I get 4 to make a raid 10 (so I get 192GB space) for the DBs
Then I create 5 Volumes on it for the 5 DBs (as I wrote in post #7)
D:\DB1
E:\DB2
F:\DB3
G:\DB4
H:\Public Folder

Then I take the remain 2 disks to make a raid 10 as well (so I get 146GB space) for the Logs
I create 5 volumes as well for the Log of the DBs
I:\Log1
J:\Log2
K:\Log3
L:\Log4
M:\Log5

Is that a solution that works and is supportet??

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Post #: 11
RE: 2 Node DAG Disk Design - 8.Feb.2012 4:25:46 AM   
zbnet

 

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Yes, that will work.

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Post #: 12
RE: 2 Node DAG Disk Design - 10.Feb.2012 12:08:40 AM   
ermanishchawla

 

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The following details may be useful to you

1. Configured first two disk in RAID 1 (Mirror) So that in event of failure of 1 disk OS will not crash at all. You can use 3G/6G SAS disk for the performance of suitable size ranging from 146GB to 300 GB for OS.

2. Configure the remaining disk in RAID 5 or RAID 6 based on your requirement.

3. Now in RAID 5 Disk Create Separate volumes Vol1= Logs of Suitable Size, You can limit the size of volume by enabling circular logging
Vol2= MB Database Volume (Primary)
Vol3= MB Database Volume (Healthy Copy of other DAG Node)

This way you will be able to achieve better control over the things.

Regards
Manish

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Post #: 13
RE: 2 Node DAG Disk Design - 10.Feb.2012 3:34:45 AM   
zbnet

 

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We already covered the requirement for the OS to be on a mirrored pair.

RAID 5 or 6 does give more space, but at the cost of reduced resilience for the data, and longer array build times in the event of replacing a disk after failure.

As far as your suggestion to implement circular logging; without a clear statement of customer requirements, I don't honestly know how you can justify stating this without outlining the side effects.  Does the customer need database backups for compliance or continuity reasosn?  If so, circular logging is innapropriate.

As for your last statement, in my opinion implementing circular logging gives you less control over things.

(in reply to ermanishchawla)
Post #: 14
RE: 2 Node DAG Disk Design - 10.Feb.2012 3:32:07 PM   
backdoor

 

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Hi there,
@ermanishchawla: thank's for your suggestion
interesting configuration as well
First question: is that solution supported?

just for my understanding
#1 and #2 are clear
#3: after I build up the raid5, I create 6 volumes (1 for Log's; 5 for DB's)than I create some foldes like mentioned in post 11 (5 folders in the volume for the log's; 1 folder in every volume for the DB's)

right??

I think circular logging will not be an option, currently we do a full backup every night, I think we will do this so anymore

what did you mean with "Vol3= MB Database Volume (Healthy Copy of other DAG Node)" ?
The DAG copies?

what are the pros and contras comparing your configuration with my??

greetings from Germany :-)

(in reply to zbnet)
Post #: 15

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