Backup Bottleneck: Why are my backups taking so long?
Most IT managers have a full schedule of ever changing daily tasks to oversee & backup is just one of many tasks.
As long as the daily backup is successful there usually isn’t a reason to spend much time reviewing the summary. Unless, of course, there is a noticeable change in performance!
For example, a daily backup that usually takes 1 hour to complete is now taking over 7 hours?
This will require some investigation and time to get to the root cause.
Here are some tips on what to look for in your investigation:
Depending on the amount of data you need to back up, a reasonable amount of network bandwidth is required. If new, high-bandwidth applications or systems have recently been introduced into the environment, your backups may be starved for bandwidth.
I/O and resources
Available disk I/O is a big factor in just how long it takes to back up your data. Particularly when backing up data sets that contain large numbers of tiny files, such as a file server or log server. Servers can only handle so many file operations a second, so other processes that are hitting the disk hard will have adverse effect on your backup performance. It’s always a good idea to use a system performance monitor to have a look at what applications are using what amounts of I/O.
Backing up wrong data
This is a problem that is all too common, especially when backing up shared systems. A certain folder might be selected for backup, but some unknowing user copies a few database dumps or other large amounts of data into the folder. If your backup times and backed up data volumes change drastically, this is usually what happened.
Traditional rotating hard disks, especially as they start nearing full capacity, tend to become increasing fragmented as time goes on. You will find that overall system performance will degrade, and this will affect your backup performance as well. Defragmenting occasionally and moving to larger capacity disks when necessary will keep things in smooth working order.
Many small files
When is a Terabyte not a Terabyte? You may be happily backing up a Terabyte worth of database dumps without an issue. You then decide to start backing up your 500GB file server. Why is it so slow? Often, it just comes down to a simple matter of iops. A low end file server with two SATA disks in a RAID1 configuration will be limited to less than 100 iops. If your file server contains several million files, the speed at which this amount of data can be backed up will be limited. Luckily, modern backup software can alleviate the pain a bit by employing advanced data deduplication technology which can avoid unnecessary file scanning and copying.