February 4, 2013 at 5:38 pm
Hi all,
I posted this initially in the cloud section but it doesn't seem to be getting any feedback here, so hopefully someone in here will have some feedback.
We provide database support for a client who are planning an AX deployment to a cloud provider. The issue I see is the expected size of the databse will reach 1 terrabyte (anticipated in first 12-24 months). Currently the cloud provider has a max presentable disk size of 250GB. I see 2 strategies:
1. Multiple datafiles of 250GB.
2. Using a windows dynamic drive to make multiple 250GB drives appear as a much larger drive(theoretically capable of housing files larger than 250GB).
The question is how does SQL treat such a dynamic drive. Can it create files of larger than 250GB if that is the maximum underlying presented disk size. The cloud provider says yes, 250GB plus files can be created - but what is actually happening under the hood? My suspicion is that capping data file size at 250GB is the safer route. Does anyone have any input on this?
Ta,
Rob
February 5, 2013 at 7:56 am
Dynamic Disks are an easy way to expand an existing drive's size but they have some inherent overhead and create a less fault tolerant environment. I would avoid them whenever possible for hosting SQL Server database files. I would go with multiple 250GB presented drives, each of which should be on redundant storage, and multiple database files. You can always add more drives and ndf files later if the data grows.
If your log needs more than 250GB initially or will need to grow beyond 250GB SQL Server supports multiple log files. SQL Server will only write to one log file at a time but it will start writing to the next ldf on another disk as needed whenever the active portion of the log reaches the end of the current ldf.
If the log file explanation was unclear let me know, hopefully it came across cleanly. Bottom line is multiple 250GB disks will do what you need and likely perform better and be more fault tolerant than a single spanned volume with multiple 250GB drives behind it.
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato
February 5, 2013 at 8:02 am
limit of 250GB? Not hosted on a virtual machine by any chance is it?
Keep well clear of dynamic disks in windows they're only designed to be used in the absence of an underlying RAID system.
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