Msg 824, Level 24, State 2, SQL Server detected a logical consistency-based I/O error: invalid protection option
Data in SQL Server is stored in 8KB pages, both in memory and on-disk. Corruption in those pages are detected using one of several different methods, configurable at the database level. The best option, and…
Convert an LSN from Hex to Decimal
Log Sequence Numbers (LSNs) can be displayed and consumed in several formats. This post shows how to quickly and easily convert between the “typical” hexidecimal format, and the equivalent decimal format. Hexidecimal format LSNs appear…
Using DBCC PAGE to view Row Details
SQL Server stores database data on 8KB pages. The details around looking at page contents are a pretty advanced subject. However, understanding some brief details about the page structure via the output of DBCC PAGE…
CHECKPOINT and Simple Recovery Model
This article shows how checkpoint and simple recovery model works. For databases configured with the “simple” recovery model, it’s important to understand how checkpoints work1 under simple recovery model to avoid running out of log…
Transaction Log Structure
Intro This post shows the internal logical structure of the SQL Server Transaction Log. The details here target SQL Server 2000 to 2017. Note that SQL Server 2019 will likely include Accelerated Database Recovery, aka…
VLF truncation in SIMPLE recovery model
I recently presented a session on log file management where I discussed monitoring and managing the logical segments of the transaction log known as Virtual Log Files, or VLFs. A great question came up about…