The absolute limit will depend on both your platform (FAS900 series, FAS250, R100, R150, R200 or F series) and ONTAP Version. Check the ONTAP release manual for your version. For example, 6.5 supports max of 28 for FAS900 & F series filers. I think this has been the same for quite a few releases.

 

RAID DP cuts that in half.

 

Seems you have two goals;

1)       Consolidate exisiting volumes into fewer, larger volumes

2)       Get some performance increase by increasing spindles

 

You can make your volumes & raid groups larger and thus get more spindles. However, there are two questions you need to answer first;

1)       Are you sure that disk I/O is the bottleneck in your DB performance? i.e. Run a statit analysis on your filer for some high and low usage periods over the next few days and examine the results.

2)       How important is volume restore time? Remember, the larger the volume, the longer it will take to restore if there is a double-disk failure. (Of course, you can always mitigate some of the risk here by upgrading to 6.5.1 and using RAID DP, however this limits you to max raid size of 14). I believe NetApp recommends to keep volumes under 0.5? TB for this very reason.

 

 

Now, if (1) is true and (2) is not so important, you still have one more thing to keep in mind;

            Increasing spindles follows the law of diminishing returns. I recall reading somewhere that the optimum raid size for performance was 10-14, anything larger than that and the performance return is exceedingly small.

 

            At one place we ran Sybase DB's on 36G disks with RAID sizes of 10 & 12 with good results. Although there are a lot of other factors that come into play with DB performance.

 

Ok, that should be enough information to help you make some preliminary judgements. Let me know how you go.

 

 

Aaron