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In my previous post on data compression, I looked at how rebuilding a table with page compression works with multiple processors via the MAXDOP option. In this post, I'll focus on what compression ratios I have seen in the real-world databases. Now, if Read More...
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In my previous post , I looked at how a typical OLTP workload may be affected by various controller cache configurations. And the conclusion was that giving too much cache (say all 512MB) to reads hurt the OLTP performance. The primary reason was that Read More...
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In my previous post on the performance impact of controller cache configurations , I presented some empirical results showing the performance impact of configuring the controller cache to various read/write settings on large sequential I/Os. Why did I Read More...
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In the next several blog posts, I’ll share with you some empirical results concerning the performance impact of configuring the read/write cache of a disk controller. In the comments on Joe Chang’s blog at this site on Storage Performance for SQL Server Read More...
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Recently, I was involved in designing a SQL2005 cluster. Let’s just say that it was going to have many more nodes until we found that we had to scale down to a 3+1 cluster because of drive letter limitation. The annoying thing is that even with a 3+1 Read More...
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A while back, I was drafted to work on some database corruption issues, and spent a good amount of time toying with the notion of database resilience. In the process, I looked at various vendor initiatives in helping to alleviate data corruption, and Read More...
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Andrew Kelly in a recent post here advised visiting/revisiting the SQL Server I/O basics, and I completely agree. A firm grasp of the basics can make it easy to understand some system behaviors that otherwise may be puzzling at times. A question that Read More...
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Right now, flash memory-based solid state drives are still more expensive than traditional disk drives in terms of the cost per gigabyte. But flash-based drives or some type of hybrid that combines both flash and traditional disk drives seem to be coming. Read More...
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In June 2006, Microsoft published a SQL Server technical paper on Physical Database Storage Design . This paper was updated in February 2007. The paper is generally well written, and the recommendations are reasonable. However, the following two specific Read More...
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There has been much discussion on the usefulness of disk queue length as an indicator of a disk I/O bottleneck. Bob Dorr, for instance, addressed this issue directly in his excellent blog, SQL Server Urban Legends Discussed . But the issue is not settled Read More...
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The best documentation on the I/O behavior of SQL Server checkpoints is found in SQL Server 2000 I/O Basics by Bob Dorr. In particular, you should read the following carefully: SQL Server uses the following steps to set up another page for flushing and Read More...
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Too many DBAs tend to view a drive presented from a Storage Area Network (SAN) as something of a monolithic nature. They look at the drive as if it had some intrinsic performance characteristics. This view doesn't help one appreciate the true performance Read More...
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How can you corrupt an online SQL Server 2005 database? Okay, why would you want to do that? Well, let's say because you want to test out some DBCC commands. If you take a SQL Server 2005 database offline, you can easily corrupt it by opening it with Read More...
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With the insert script and the test configurations in my previous posts , the best data load throughput was 24GB in ~7 minutes when the checkpoint (and/or transaction commit) batch size was set to 100,000 ~ 1,000,000. That was the best result when I was Read More...
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In my previous posts ( 1 , 2 , 3 ), I focused on the performance behavior of setting the checkpoints and transaction commit sizes to once every 16 inserts and once every 100,000 inserts. A question remains: what is the most optimal size? In other words, Read More...
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