Sunday, May 22, 2011

Free Tool : JKFragmenter

JKFragmenter is a free tool that allows you to deliberately break up your files, scattering them all over the drive! I'm glad I found it, as I can emulate the situation on some servers I have come across recently.

Basically the data files on the forementioned servers were not presized so along with some bad autogrowth settings. To illustrate the performance impact this had on sql, I set up a database and deliberately fragmented the .MDF and .LDF files on the filesystem (I set the DB offline whilst I did so).

It is a command line tool, taking the form -
jkfragmenter -p 100 -s 500 filename
-p = fragment count to split file into. Default is 10. Use 0 or 1 to defragment.
-s = size in kilobytes, Default is 1000Kb (approx 1Mb)

Output and screenshot of usage -

c:\tools>jkfragmenter -p 10 "C:\Data\sql_tools.mdf"
Fragmenter v1.2, 2008 J.C. Kessels

Commandline argument '-p' accepted, parts = 10

Processing: C:\Data\sql_tools.mdf
File already exists.
Fragment list (before):
Extent 1: Lcn=17248693, Vcn=0, NextVcn=250
250 clusters, 1 fragments.
Fragmenting:
Largest gap: 28827794 - 29342048 (514254 clusters)
Moving 25 clusters from offset=0 to LCN=29084908
Largest gap: 29084933 - 29342048 (257115 clusters)
Moving 25 clusters from offset=25 to LCN=29213478
Largest gap: 28827794 - 29084908 (257114 clusters)
Moving 25 clusters from offset=50 to LCN=28956338
Largest gap: 12795714 - 12978718 (183004 clusters)
Moving 25 clusters from offset=75 to LCN=12887203
Largest gap: 13031538 - 13212410 (180872 clusters)
Moving 25 clusters from offset=100 to LCN=13121961
Largest gap: 28956363 - 29084908 (128545 clusters)
Moving 25 clusters from offset=125 to LCN=29020623
Largest gap: 29084933 - 29213478 (128545 clusters)
Moving 25 clusters from offset=150 to LCN=29149193
Largest gap: 29213503 - 29342048 (128545 clusters)
Moving 25 clusters from offset=175 to LCN=29277763
Largest gap: 28827794 - 28956338 (128544 clusters)
Moving 25 clusters from offset=200 to LCN=28892053
Largest gap: 3669806 - 3794003 (124197 clusters)
Moving 25 clusters from offset=225 to LCN=3731892
Fragment list (after):
Extent 1: Lcn=29084908, Vcn=0, NextVcn=25
Extent 2: Lcn=29213478, Vcn=25, NextVcn=50
Extent 3: Lcn=28956338, Vcn=50, NextVcn=75
Extent 4: Lcn=12887203, Vcn=75, NextVcn=100
Extent 5: Lcn=13121961, Vcn=100, NextVcn=125
Extent 6: Lcn=29020623, Vcn=125, NextVcn=150
Extent 7: Lcn=29149193, Vcn=150, NextVcn=175
Extent 8: Lcn=29277763, Vcn=175, NextVcn=200
Extent 9: Lcn=28892053, Vcn=200, NextVcn=225
Extent 10: Lcn=3731892, Vcn=225, NextVcn=250
250 clusters, 10 fragments.

Finished, 1 files processed.

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