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Beware of Shifting SAN
Let’s say you are trying to determine the performance impact of a neat database design change you have just devised on an application. So you run some tests with the existing design and the tests run...
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Should I Use a Windows Striped Volume?
In Windows Server 2003, you can use the Disk Management console to create a striped volume over multiple dynamic disks (well, you can also create a mirrored, a RAID-5 volume, etc). If these disks (or...
View ArticleHow did Random I/Os Outperform Sequential I/Os?
Recently, when I was doing some I/O performance tests on an I/O path, I found that 8K random reads (and writes) significantly and consistently outperformed 8K sequential reads (and writes) in terms of...
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Performance Impact: file fragmentation and SAN -- Part I
1KB Sequential Writes It’s well known that disk I/O performance can be severely impacted by fragmentation at the file system level. In other words, when a file is allocated space from many small...
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Performance impact: file fragmentation and SAN – Part II
1KB Sequential Writes on DAS There were some questions about the use 1KB sequential writes in my previous post to test the performance impact of file fragmentation on a drive presented from a high end...
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Performance Impact: file fragmentation and SAN – Part III
256KB Sequential Reads In my two previous posts (1, 2), I highlighted the fact that while file fragmentation had a huge adverse performance impact on directly attached storage (DAS), it did not have...
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Performance impact: file fragmentation and SAN – Part IV
Lies, damned lies, and statistics! If you have read my three previous posts (1, 2, 3), you may walk away with an impression that on a drive presented from a high-end enterprise class disk array,...
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Performance impact: file fragmentation and SAN – Part V
SQL Server workloads So far, the discussions in all the previous posts (1, 2, 3, and 4) on the performance impact of file fragmentation on a drive presented from a high-end enterprise-class disk array...
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