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SQL has become the pre-eminent component for database procedures such as, database handling and combining all the vital information into a database system. That’s why database administrators should have ample training and information about SQL.
Unfortunately, there are some common SQL issues most database administrators face while SQL backup. Sometimes the situation is not as bad as you might be thinking.
Therefore, here, we have listed some common SQL backup issues and simple solutions to mitigate them.
Table of Contents:
- Reason 1: System Outage And Restoration
- Reason 2: Low Space “Insufficient Disk Space for Backup”
- Reason 3: Insufficient Transaction Log Space
- Reason 4: (Backup Across The Network) Timeout Errors and Logs Fail
- Reason 5: The log or differential Backup Cannot be restore
- Reason 6: Earlier State Error
- Reason 7: Wrong Server Execution
- Conclusion
Reason 1: System Outage And Restoration
In a sudden system outrage or file misplacement, previous data backup could be a life savior. But, many times .MDF or .LDF files become unresponsive or database completely disappear. This is because the SQL server requires a specific type of backup.
Many people are unaware of the fact that SQL server locks a database file which causes a file backup system to skip these files. Therefore, a file error can be displayed when you open such a file. File backup systems can detect a file lock, but they back it anyway.
One more issue is latency. Database professionals have experienced slow backups, taking hours and hours to complete the process.
Solutions 
As mentioned above, SQL servers follow a strict method to create backups, right into the very heart of the product “backup database”.
This method, although still aptly compatible with 2008R2, was first published in 2005. With this method, the SQL server not only creates files for you to restore upon need but also figures out all your transactions.
Due to its efficiency, it is still popular for creating backups with SQL server.
Apart from that, in the matters of latency or slow backups, the user can view the full life cycle, starting from reading the data files along with compression to the data destination.
Moreover, there are various third-party tools available that may help to identify and to cater to any bottleneck issue.
Reason 2: Low Space “Insufficient Disk Space for Backup”
Database administrators commonly experience Space error or backup failures.
This happens when you have an overloaded system or due to any unintended use.
For instance, when the transaction log is full, it may cause the transaction error.
Whereas, some errors are related to the drive space and situations when some factors cause backup data origin or destination absence.
Solution
For resolving this issue, data administrators should monitor the drive space and the database sizes which directly impact database size. This step seems general, but only such preventions can save you from sudden outrage. Another necessity is to check the backup clean up process.
Most of us neglect the issue or might forget the cleanup process for a long period. Therefore, it is necessary to implement additional validation which highlights the backup age and sends you an alert for this as well as deletes old backup files after your confirmation.
Also, have in mind that you are not clearing the new or important backup files which you might need in the future.
Reason 3: Insufficient Transaction Log Space
With a full transaction log, you can’t run the backup process. That’s why you sometimes get an alert of transaction hindrance, highlighting insufficient space in the transaction log or the drive where the log is stored.
In this case, the database might provide you a chance to run SELECT queries, but anything which allows data modification is completely blocked and users could notice the problem.
A full backup couldn’t fix the issue because it can’t write to the log. Also, the server restart or file shrinking could not help much. But why is this happening?
The Recovery Model is set to full by default. Therefore, if you haven’t changed anything while starting database creation, then the system’s Recovery Model will have the same status.
Recovery Models are of three kinds; full, bulk-logged, and simple.
The full and bulk-logged are almost the same in all intents and functions, and as we are not going deep in this article, so we will consider them as same.
When the Recovery Model is set to full, it’s considered that whenever you would restore the database, then only you would restore the recovery model.
In simpler words, it is maintaining the data log with every transaction you have done and stay as it is until you run a log backup.
This means it is necessary to run log backup independently from the full database backup you are running already. Therefore, a log will go unaffected by the full database backup.
Solution
You have two ways to prevent this situation. You can either switch to Simple Recovery Model or set up an independent set of log backup.
Simple Recovery means that the transactions are written to the log, but after being written, they are purged as soon as a checkpoint occurs. The second one requires regular backup, and the running process depends on two things; the number of transactions and the limit of your business recovery requirements.
One main reason due to which the Recovery Model is neglected or avoided is, it takes away the capability to restore the database at any time. On the other hand, having transaction logs that can be backed up is advantageous because you can restore the database right before an outrage.
However, to do this, a good set of log backups and a tail log (where possible) are a must. Tail backup is done before bringing the machine offline while assuming it online. These preventions will help you to restore your system up to the last log backup or to any moment with a tail log.
Reason 4: (Backup Across The Network) Timeout Errors and Logs Fail
When you back up across the network, you face extremely slow backup speed. The issue could become so serious that sometimes you experience the log fail or timeout error.
Also, the slow backup process could affect your SQL server, and the system speeds up only when you stop the backup.
Therefore, in such circumstances, your network can encounter excessive load.
Backups usually run slow on the network because of the congestion they mostly have. For instance, social networking sites, games, and other sorts of contentions.
On the other hand, when you backup on a local disk or SAN via a dedicated fiber channel, the process is as fast as the disk can handle. Server downtime could also be a reason for sudden errors and issues while SQL database backup.
However, you can’t completely eradicate this risk. For instance, a web study published by Rol John (a SQL database admin) shows the uptime of various web hosts, but not a single provider has 100% uptime.
Solution
There is a two-step solution for this particular issue. This might be a bit lengthy process, but through it, you could successfully complete the backup process.
First backup to the local disk and copy the file across the network. This process can be helpful if you have a lower disk space. However, if disk space is not an issue or you can afford to buy another then you could backup on disk and leave it there.
Reason 5: The log or differential Backup Cannot be restored
Differential backups are a lost cause without the full backup. Most people tend to misunderstand their purpose and try to restore files through them even when the full backup is lost.
Even when people run a full back up before running a thorough differential backup, they don’t leave the database in the recovering state, which is vital to apply differential or log backups. Therefore, these could be the issues that hinder the SQL backup process.
Solution
The only solution is that you run full backups. As differential backups rely so profoundly on full backups, it is crucial to have the full backup ready. Therefore, if you ever want to restore files, you can have differential backups and full backups running in combination.
Furthermore, while restoring the full back up, it is essential to leave it in a recovering state so that differential can be applied.
(Script will look like this)
|
RESTORE DATABASE MovieManagement FROM DISK = 'g:\bu\MovieManagement.bak' WITH REPLACE, NORECOVERY; |
Through this, the database will be restored and will be left in the recovering state simultaneously. It is now that you can apply differential backup to the process. Moreover, having the database in the recovery option is crucial to restoring logs. This can be done through the “no recovery” option.
Reason 6: Earlier State Error
It is not necessary that the things go on smoothly even if you have been smart enough to follow through with every process studiously. You have the differential and the full back up in place; there is no disk space issue or any other problem as you have monitored everything.
Despite this, you are unable to restore your data and facing an “earlier state” error. This means that your differential backup cannot be restored because it is initially not been stored at the original earlier state.
This usually happens if the backup chain breaks down. The error appears because the differential restores operation is aware of its parent differentia base. It thus keeps an evident track of the Log sequence number (LSN), and through it, the error is generated.
Solution
To get rid of this issue you have two options that you can use depending upon your situation. Some people just want the backup restored because it is just a mere precaution amidst the rollouts or updates. In such a case, you run a snapshot backup which is easy to generate and get the job done.
However, if you need a full back up, then you can create a backup using the “copy only” option. But, it is essential to notice that backing up through this method won't update the differential base for that specific file. It also won't affect the log chains.
Reason 7: Wrong Server Execution
Another major failure you can face is when you accidentally restore data in the wrong end server.
Although this is not really a backup issue, considering it is an almost every day occurrence, we decided to highlight it.
This happens when you usually are not paying close attention to what you really are doing, and thus you end up in a fix.
However, excuses aside, this still is a problem that must take care of.
To get rid of this issue you have two options that you can use depending upon your situation. Some people just want the backup restored because it is just a mere precaution amidst the rollouts or updates. In such a case, you run a snapshot backup which is easy to generate and get the job done.
However, if you need a full back up, then you can create a backup using the “copy only” option. But, it is essential to notice that backing up through this method won't update the differential base for that specific file. It also won't affect the log chains.
Solution
One way out of this issue is to have a different login to every server. Along with that, you can use an individual copy of SSMS through the Run As command.
Also, you can have separate color codes for every server, and you can color the information bar present at the bottom of the query window in the SSMS.
The query window is present in the “Connect to Database Engine” window in the “Connection Properties” tab. With this, you can get a more organized view of your setup.
Apart from that, another way to get rid of the issue is to stop using the rollback immediately to get rid of users out of the system.
It is better to call them and ask them to log out of the system or just use the individual kill statement method.
Conclusion
Backup issues can occur due to various reasons. However, getting a grasp of the most common matters can save you from a lot of hassles. With a little knowledge and smart approach, you can smartly get done with your job.
