processing writes requests in data=journal,sync mode

[Boris Erl]

Hi,

We are currently doing SpecSFS comparison benchmarking to evaluate
advantages of FS journaling to NVRAM card versus journaling to hard disks.
We compare NFS performance for Linux file server with ext3 file system in
‘data=journal’ mode for three different locations of the file system
journal:
   - inside main file system
   - on a dedicated HD
   - on an NVRAM PCI card
The file system is mounted and exported in ‘sync’ mode.

We assume that ext3 file system works in the following way:
  - synchronously writes data to file system journal
  - acknowledges to the client that NFS operation is completed
  - at some time asynchronously writes data to the main file system

Could somebody confirm or correct our assumption above?

Sincerely,

 Boris Erlikhman
 borise at comcast.net