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How to Fix Exchange Error Code 1018?

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Microsoft Exchange server consists of an email-based collaborative platform for business service. The ongoing and ingoing communication messages of the server are stored in the mailbox of EDB database. These EDB databases are prone to corruption due to unpredictable reasons such as dirty shutdown, virus attacks, human errors, etc. Error –1018 (JET_errReadVerifyFailure) is one such error that every system administrator of Microsoft Exchange must have been conversant. It denotes that an Exchange database file has been impaired by a disruption or a complication in the intrinsic file system or hardware.

UNDERSTANDING THE BASICS OF DATABASE STORAGE

Microsoft Exchange server implements a data storage technology known, as ESE (Extensible storage engine) .Its main function is to store and retrieve data through sequential & indexed access. The Exchange store forms the top-most level of the ESE which stores data. The EDB database file is divided into tables, which is responsible for making the database more relational in certain aspects. A single email message may be typically stored across two or more tables.

In an EDB database, the first  two physical pages consist of information that is related to page header. Page number -1 consists of database header  and page 0 contains an exact replica of page number -1.It is known as shadow header. The third page of the EDB file stores the real data. For efficient management of data storage and retrieval Microsoft has evolved the B-tree structure.

The B-tree structure that is employed by ESE is considered as B+tree and is a slight alteration of B-tree as it  includes pointer to previous pages and next pages. This helps in fast traversal of the tree in any kind of database operations. Each page in a database can store up to 200 page pointers. This allows the B-tree to work out quickly.

In a typical B+tree, all the data is present on the leaf nodes whereas the upper two levels contain only structural related information. If a  particular leaf node  of the B+ tree is impaired because of corruption issues related to disk then possibly there is no loss of data. Nevertheless ,if the structural pages are damaged, then there is a higher probability that the pages are completely lost. For this ,the system administrator has to run the ESEUTIL/P to repair the B+tree.

Examination of the Database

Each page consists of data and at the beginning of the page, the page header is present which consists of header information that is crucial for the working of database. The page header further consists of  a page identifier, a pointer which aims to the next page and a pointer which takes to the previous page and a checksum.

Occurrence of Error 1018

The errors 1018 generally occurs  in one of the three siuations mentioned over here:

When taking an online backup

When executing offline maintenance by ESEUTIL /D

When the page is read from the store to disk

If the Exchange server1018 occurs,ESE reports the error to the Application event and again ties to read the page instantaneously.Practically,it tries to read the page 15times more just to ensure that the first reading of the page is false positive.So,normally one can overview upto 16 separate error events in the application event  record for one page error.

If the page which contains error is an email or its attachment,the error 1018 will be reported whenever the user will make an attempt to read out the message.However,the message won’t get open.If the page is read out in the event online backup,the backup will be terminated and an event will be reported to Application event log.The data present in the page  will appear as white space which tools like ESEUTIl can  detect in offline conditions.

Enabling Page Checksum

Each page in the EDB database holds a checksum in its header. Each time the Store takes down a page from memory to disk, it determines the checksum of the page. The checksum is calculated on the basis of a simple algorithm which is generally based on the no. of bits present in page and then it writes the checksum  into the page header before it takes down to the disk.

When the store reads page from disk, the checksum is again calculated by employing the same algorithm to assure that the data which was written onto the page has not been altered. If the enumerated checksum is not similar to the checksum present in the page header, the page is taken into consideration and it is believed some fault must have occurred.

Alternative Method for Executing a Checksum Test

Checksum involves a mathematical procedure for substantiating the incorruptibility of a file. A checksum can be carried out in a number of methods. The Exchange server authenticates all the pages present in the EDB database, checkpoints and log files. This method serves as a convenient approach to ascertain that whether the database has any faults which may require immediate action to repair it.

For the checksum test mode

For performing checksum test on mailbox database

For  repairing page-level corruption,Exchange server has an inbuilt utility known as ESEUTIL utility. However, ESEUTIL alone cannot be used for the purpose of repairing  because it results in logical corruption of the database. For effective repairing of the database damaged due to page-level corruption, a system administrator has to opt for  ESEUTIL utility followed by defragmentation and then repairing by ISIINTEG utility.

 
   
 

The above process generally appears to be complex and time taking for a user to execute. In such situation, the user can resort for third-party tools. A number of third-party tools are available in the market which can assist in the repairing of database from page-level corruption. One such tool is QuickData Exchange EDB Recovery Software so by doing a Google search user can find the right application.

   
 
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