Learn more on How to take performance bottlenecks of networks backup

Learn more on How to take performance bottlenecks of networks backup

At some point, however, the technical boundaries for increasing the performance of backup are reached. When talking about technical boundaries, we should differentiate between application-specific boundaries (Section 7.6.1) and those that are determined by server- centric IT architecture

Application-specific performance bottlenecks

Application-specific performance bottlenecks are all those bottlenecks that can be traced back to the 'network back-up' application. These performance bottlenecks play no role for other applications. The main candidate for application-specific performance bottlenecks is the metadata

database. A great deal is demanded of this. Almost every action in the network back- up system is associated with one or more operations in the metadata database. If, for example, several versions of a file are backed up, an entry is made in the metadata database for each version. The back-up of a file system with several hundreds of thousands of files can thus be associated with a whole range of database operations. A further candidate for application-specific performance bottlenecks is the storage hierarchy: when copying the data from hard disk to tape the media manager has to load the data from the hard disk into the main memory via the I/O bus and the internal buses, only to forward it from there to the tape drive via the internal buses and I/O bus. This means that the buses can get clogged up during the copying of the data from hard disk to tape. The same applies to tape reclamation.

Performance bottlenecks due to server-centric

IT architecture In addition to these two application-specific performance bottlenecks, some problems crop up in network back-up that are typical of a server-centric IT architecture. Let us mention once again as a reminder the fact that in a server-centric IT architecture storage devices only exist in relation to servers; access to storage devices always takes place via the computer to which the storage devices are connected. The performance bottlenecks described in the following apply for all applications that are operated in a server-centric IT architecture.

Let us assume that a back-up client wants to back data up to the back-up server . The back-up client loads the data to be backed up from the hard disk into the main memory of the application server via the SCSI bus, the PCI bus and the system bus, only to forward it from there to the network card via the system bus and the PCI bus. On the back-up server the data must once again be passed through the buses twice. In back-up, large quantities of data are generally backed up in one go. During back-up, therefore, the buses of the participating computers can become a bottleneck, particularly

if the application server also has to bear the I/O load of the application or the back-up server is supposed to support several simultaneous back-up operations. The network card transfers the data to the back-up server via TCP/IP and Ethernet. Previously the data exchange via TCP/IP was associated with a high CPU load. However, the CPU load caused by TCP/IP data traffic can be disregarded with the increasing use of TCP/IP offload engines (TOE) (Section 3.5.2 'TCP/IP and Ethernet as an I/O technology').