Performance Tuning with SQL Server Dynamic Management Views

The results are as follows:
Chapter 6: Physical Disk Statistics and Utilization
drive RatioOfReads RatioOfWrites TotalBytesRead TotalBytesWritten
----- ----------------- --------------- -------------------- --------------------
E 0.509947179620… 0.49005282037… 324253917696 311603933184
F 0.953302196684… 0.04669780331… 2213262221312 108417335296
H 0.376100820227… 0.62389917977… 344707538944 571822073344
I 0.922886044827… 0.07711395517… 1316300808192 109986668544
J 0.708701451352… 0.29129854864… 381697171456 156889522176
K 0.974068440224… 0.02593155977… 1040343924736 27695939584
As you can see, some of the drives are heavily skewed towards reads (92:8 for the I: drive),
whereas H: is skewed towards writes. Do any of these values indicate a potential problem?
As the old DBA saying goes: "It depends." In this case, the H: drive contains tempdb,
so heavy writes are to be expected. The E: drive, with a ratio of 51:49, is where all the
tempdb logs reside.
Of considerable concern are the I:, F:, and K: drives, where we have a tremendous amount
of reading taking place in each case. These drives house the data for one of our heavy
use databases and I would certainly like to investigate further to see if the amount of
data being read could be reduced. The next step is to obtain the read:write ratios for this
database in terms of the number of read and write operations. If this method reveals a
ratio much closer to 50:50 then we know that reads are reading a disproportionately high
amount of data.
Number of read and write operations
Listing 6.19 takes exactly the same form as Listing 6.17, except that it returns the number
of reads and writes as a proportion of the total number of reads and writes.
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