Flat files vs. Exchange data

[Greevous]

Why is it that my average exchange store backups go at 1700MB/min and my average file backups go at about 200MB/min.

Backup Server:
All servers that need to be backed up are on a private Gigabit Ethernet connection.
The Backup Tape Drive is an Certance Ultium LTO2
The File server and Exchange server are identical
DL380 G2 machines.

Any thoughts?


Greevous

 

[fraxx]

The Exchange store backup is faster because it's a single operation with only a few steps; "open store", "read entire store", "close store". You're done.

To backup the file system(s) you need to open file 1, read file 1, close file 1. Open file 2, read file 2, close file 2. Repeat as needed, usually millions of times.

This filesystem overhead is causing the performance issues. That coupled with the fact that 200MB/min is far less than the rated transfer speed of an LTO2 (which is about 1800MB/min native, higher with compression) makes the tape not stream, causing even worse performance.

Not much can be done really. NTFS is NTFS, a lot small (<100kB) files will cause backup performance to suck. Admitedly, most if not all filesystems today has these issues, more or less. You can probably mittigate the overhead to some extent by backing up to disk, thus eliminating the LTO2 sub-optimal usage pattern. Backup Exec 9.x has this feature.

Other options are to investigate snapshot backups, if you're on Win2k3 you can look into VSS.
/charles