Question
How fast is the Files Restore in CDP 3.0? Is it faster than in CDP 2.x?
Answer
Using CDP 3 Enterprise Edition (with compression) will take 10 hours to restore 10 Million 1 KB files with a Linux destination for the Restore. Average throughput performance is 3 MB/s in this case.
On the same servers, restoring one 10 GB file transfers at 30-35 MB/s.
Reading Files
The CDP 3 Disk Safe can actually read the files much faster than CDP 2.x. See also: Files Restore Speed, Files Restore Is Very Slow.
CDP 3 crawls all the files you want to restore to total the file sizes before it restores, giving you an accurate progress bar. Opening 10 million files (Inodes) to get their file size takes 7 minutes.
When CDP system reads files in the Disk Safe, the operating system is not involved. CDP just fetches 32 KB Disk Safe pages from a file on Disk.
Creating Files
When we have to write the files, we need to involve the operating system. Restoring those 10 million files takes as much as 10 hours for only 124 GB of data. It is because we call Open() or CreateFile() and the file system has to journal each operation as a transaction. It is an OS and file system limitation.
Compare: When we restore one 10 GB file on the same servers, we call Open(O_CREATE) once and then write 10 GB of data. In this case, the "penalty" for creating a large file is negligible.
 | Note The performance measurements were completed on two high performance servers with simple direct attached SCSI disks on a Gigabit Ethernet Switch. |
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