Pageiolatch sh what is

High values may indicate bottlenecking or excessive pressure on the database engine: Avg. As a last resort, review whether disk resources are adequate for your server load: If your disk drivers and BIOS are out of date, consider upgrading. See Storage Top 10 Best Practises. Didn't find what you were looking for? Visit the Redgate forum Contact Support.

Product Articles Tips and how-to guides for Redgate products. Implicit conversions are an insidious problem caused by a mismatch between the search predicate data type and the data type of the column being searched, or a calculation being performed on the table column rather than the search predicate.

In either case, SQL Server cannot use an index seek on the table column and must use a scan instead. This can crop up in seemingly innocent code, and a common example is using a date calculation. If you have a table that stores the age of customers, and you want to perform a calculation to see how many are 21 years old or over today, you might write code like this:.

This can be solved by moving the calculation to the other side of the operator:. In terms of when a basic column comparison requires a data type conversion that can cause an implicit conversion, my colleague Jonathan Kehayias wrote an excellent blog post that compares every combination of data types and notes when an implicit conversion will be required.

In my experience they're usually caused by something to do with SQL Server and that's where I'd start troubleshooting. As far as general wait statistics are concerned, you can find more information about using them for performance troubleshooting in:. In the next article in the series, I'll discuss another wait type that is a common cause of knee-jerk reactions. Until then, happy troubleshooting! Paul could you confirm if it is true?

When dirty data pages write to disk, does it require latches? Yes, when dirty page is written to disk is requires a buffer latch. Is Paul Randal using a third party tool? Never thought I see it. Don't forget about PS, nothing from you on there for awhile.

Very good and informative post. I have seen this happen multiple times either because of parameter sniffing or implicit conversion. I'm no DBA but I'm looking at an application performance issue which has taken me to this blog post.

To make this simple to understand, lets explain this in an example. Page latches are actually light locks that are not configurable, placed by SQL Server internal processes as a way of managing access to the memory buffer.

In short, the answer is no. In such cases, checking the S. Self-Monitoring, Analysis and Reporting Technology log should be the first step. Another issue, very often overlooked is heavily fragmented disk. But there is often misconceptions between load balancing using physical and logical disk drives. The following use case will help in understanding the problem and a provide potential solution. RAID arrays with multiple discs are quite common in larger organizations.

In the following example, the RAID 5 array with 4 hard drives will be taken as an example. What must be clear here is that those partitions are actually logical, not physical partitions, as they share the same raid array and thus the same four physical disks — logically split RAID 5 array into 3 partitions.

The RAID array for an operating system represent the single disk drive and it is not possible for OS to distribute specific data to a specific physical drive. In such configurations, the different parts of the software systems are putting the pressure on each other, but also the different parts of the same software can conflict with each other I.

The principles of the RAID system itself will not be explained here any deeper, as it is not of particular interest for understanding the main problem.

The most widely used and recommended scenario would be the following. Set the Operating system on a dedicated RAID 1 array as minimum one physical drive is also acceptable but risky solution. Again, one physical drive is acceptable, but it can pose the risk. Set the transaction log files on a dedicated RAID 1 array. RAID1 is the recommended for storing the transaction log files. In an ideal scenario the memory buffer should be big enough to store all the necessary data for work that SQL Server has to perform.