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January 30th, 2008 19:00
Replistor Storage Design and Replication
We are considering implementing Replistor over a WAN for Exchange 2003, SQL 2005, SQL 2000, and file and print servers.
The Replistor docs on PowerLink are good concerning the implementation but are not clear about the upfront storage design.
1. On the primary array are any additional LUNs required for each source LUN that will be replicated? Is a LUN for tracking changes for each source LUN required or does the kernel cache do all of this for you?
2. On the target array do the replistor target LUNs have to be the exact same size or can they be larger too?
3. Do you recommend using VSS copies on the target side in case of corruption on the replistor target LUN? Is the best practice to use 60-100% of the target LUN size for the VSS copy?
4. Using Exchange 2003 as an example which is the recommended replication method between these 2 options:
Option 1. Use Replication Manager for local clones for the databases and logs and then SAN Copy the data to the target DR array once per day and then use Replistor to mirror logs to shorten the RTO/RPO time.
Option 2. Use Replication for local replicas/clones and use Replistore for both the data and logs and not use SAN Copy at all. What are the advantages/disadvantages between these 2 options?
Thanks in advance for your help.
The Replistor docs on PowerLink are good concerning the implementation but are not clear about the upfront storage design.
1. On the primary array are any additional LUNs required for each source LUN that will be replicated? Is a LUN for tracking changes for each source LUN required or does the kernel cache do all of this for you?
2. On the target array do the replistor target LUNs have to be the exact same size or can they be larger too?
3. Do you recommend using VSS copies on the target side in case of corruption on the replistor target LUN? Is the best practice to use 60-100% of the target LUN size for the VSS copy?
4. Using Exchange 2003 as an example which is the recommended replication method between these 2 options:
Option 1. Use Replication Manager for local clones for the databases and logs and then SAN Copy the data to the target DR array once per day and then use Replistor to mirror logs to shorten the RTO/RPO time.
Option 2. Use Replication for local replicas/clones and use Replistore for both the data and logs and not use SAN Copy at all. What are the advantages/disadvantages between these 2 options?
Thanks in advance for your help.
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dramjass
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January 31st, 2008 13:00
2. If the LUN's you are talking about is for the Exchange, SQL or file data, then yes, relatively the same size. For Exchange and SQL, it is mandatory that the data gets replciated to the same location on the Target. If you do not have sufficient space, then you are talking about potential data loss b/c the disk is not large enough.
3. VSS is an add-on feature so you can get different point in time copies of the data. It is a busines decision whether to use it or not. I can not re-call the size recommendations. Microsoft has some good articles on sizing and accommodating for shadow copies.
4. Option 1 gives you mostly hardware based replication as opposed to 2 that is software based.
Each have their pluses and minuses for administration. I have seen both methods work great for a DR solution.
I guess the best advice is to test them out to see what gives you what you are looking for.