SQL Server：为什么备份速度这么慢？

Question

I have a backup query like this:

BACKUP DATABASE @temp_baza TO DISK = @temp_bak
BACKUP LOG @temp_baza TO DISK = @temp_log

It is run by sqlcmd like this:

sqlcmd -l 120 -S %SQL_SERVER% -i %KOPIA_KATALOG%backupPELNY.sql 
       -o %KOPIA_KATALOG%output_PELNY.txt -v NAZWA_BAZY="%NAZWA_BAZY%" 
       -v KOPIA="%PELNY_KOPIA%\"
       

In output_PELNY.txt I have this kind of results:

BACKUP DATABASE successfully processed 645127 pages in 2819.651 seconds (**1.787 MB/sec**).

or

BACKUP DATABASE successfully processed 26338 pages in 227.348 seconds (**0.905 MB/sec**).

Main DB is on one Disc, backup is on second disk.

When I use Explorer to copy files between these two disks, I get a transfer speed of approximately 100 MB/s.

QUESTION:

Why is the backup speed so slow - I mean less than 3MB/s?

REMARKS:

• Windows 2012 Essential + SQL Server 2008 R2 EXPRESS
• Intel XEON E3-1270 v3 + 16GB RAM

Answer 1

SQL Server 2008 R2 Express has the following limitations:

• Constrained to a single CPU (this limitation was raised in 2012 to "The lesser of one socket or four cores", so multi-threading is possible)
• 1GB RAM
• 10GB database size (per database)

So your backup is likely to be CPU bound and/or memory bound.

(Of course, it raises the obvious question: Why are you using an express version on your server? and why not a later SQL Server version?)

Ref.: SQL Server 2008 R2 Express Database Size Limit Increased to 10GB :

What about CPU and memory limits? Are any other limits changed in SQL Server 2008 R2 Express?

• No, the database size limit is the only limit we updated in SQL Server 2008 R2 Express. SQL Server 2008 R2 Express is still limited to 1 CPU and 1 GB of RAM.

Answer 2

To solve your problem, please refer to the following links:

1. Options to Improve SQL Server Backup Performance
2. Is your SQL Server backup running slow? Here's how you can speed it up
3. Super-Fast Backup and Restore Throughput for SQL Server
4. MS SQL Server backup optimization
5. How to Make SQL Server Backups Go Faster

Below are some sample queries for download

To solve the problem, I suggest that the following part of the query:

backup database DBNAME to disk='C:\1\DBNAME.bak' with buffercount=16 ,maxtransfersize=4194304