The primary difference between traditional progressive incremental backup and journal based backup is the method in which the client uses to determine what objects to backup or expire.
Progressive incremental backup obtains the backup candidate list by building and comparing the list of active previously backed up objects stored on the TSM server with the list of objects currently residing on the local filesystem. The local object list is built by scanning the entire file system, the server list is received over the network, and the candidate list is built by comparing the two lists. All three lists reside in memory until the backup is completed. Journal based backup derives the backup candidate list by contacting the TSM journal daemon and processing the contents of the particular file system journal. The journal daemon is local process (service) which maintains journal databases for specified filesystems by monitoring the file system for change activity. The performance saving in terms of both memory, i/o, and network traffic for journal based backup is that only objects which are actually backed up/expired are processed, whereas progressive incremental has to process the entire file system. So the benefit is really only realized when backing up file systems with a very large number of objects with a small to moderate amount of daily change activity (for example, a file server with 2 million objects of which only about 5% to 10% change daily). Smaller file systems which have high volumes of change activity probably will not see that dramatic of an improvement over traditional progressive incremental backup Pete Tanenhaus Tivoli Storage Solutions Software Development email: [EMAIL PROTECTED] tieline: 320.8778, external: 607.754.4213 "Those who refuse to challenge authority are condemned to conform to it" ---------------------- Forwarded by Pete Tanenhaus/San Jose/IBM on 06/03/2002 01:40 PM --------------------------- John Bremer <[EMAIL PROTECTED]>@VM.MARIST.EDU> on 06/03/2002 12:58:56 PM Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] cc: Subject: Re: Journaling Just trying it on a couple of Win2K machines, I don't see such a dramatic performance boost. However these are clients with only several thousands of files, not millions. At 09:43 AM 6/3/02 -0500, you wrote: >Can anyone share their thoughts, opinions, war stories on Journaling for >Windows NT4.0 and W2K clients?? > >Thanks, > >Matt Adams >Tivoli Storage Manager Team >Hermitage Site Tech >Deloitte & Touche USA LLP >615.882.6861 > >- This message (including any attachments) contains confidential information >intended for a specific individual and purpose, and is protected by law. - >If you are not the intended recipient, you should delete this message and >are hereby notified that any disclosure, copying, or distribution of this >message, or the taking of any action based on it, is strictly prohibited.
