On Wednesday 03 February 2010 15:47:32 Pascal Vandeputte wrote: > Eric, Kern, > > Thanks a lot for your concise and clear answers! I'm really itching to > thoroughly start testing Bacula now.
Thanks for the encouragement. > > If it works as well as you describe, and I expect it will, I honestly > believe those VirtualFull + Accurate features should be advertised a lot > more. Seriously :-) Yes, you are absolutely right. My problem is that I am not very good in marketing and sales -- however, I will pass your comments on to the Bacula Systems guys, who love to do those things. I think a lot of people would be interested to learn about some of the more "advanced" features in Bacula (and by the way, we are planning a lot more ...) Best regards, Kern > > Thank you for your time, > > Pascal > > On 02/03/2010 02:58 PM, Kern Sibbald wrote: > > On Wednesday 03 February 2010 13:59:59 Pascal Vandeputte wrote: > >> Dear Bacula developers, > >> > >> A few years ago I deployed IBM Tivoli Storage Manager in the company I > >> worked for at the time. Since then I've never really encountered a > >> backup product that could match it in terms of speed or resource > >> utilization, which can be entirely attributed to the "progressive > >> incremental" backup strategy it uses. A file is never transferred over > >> the network twice, TSM always takes incremental backups and keeps track > >> of files it already has somewhere in its backup pool by using a > >> relational database (IBM DB2 since TSM version 6). For a longer > >> explanation, see > >> > >> https://agora.cs.illinois.edu/display/tsg/Progressive+Incremental+Backup > >>s+e xplained > >> > >> Only new files are transferred to backup storage, files which have > >> disappeared from the host since the previous backup are marked inactive > >> and eventually purged from backup storage depending on the defined > >> retention policies. It backs up to disk at night for speed, and > >> transfers from disk to tape during working hours in a FIFO manner. This > >> way restores are often almost instantaneous because the recent backup > >> data is still on disk. Other daytime tape maintenance operations involve > >> the creation of an off-site copy of the primary storage pool tapes > >> (which are always on-line (!), your tape library must be large enough to > >> accomodate this), reclamation (freeing tapes with mostly expired data) > >> and collocation (moving data from a specific host on as least tapes as > >> possible). > >> > >> The system works really well. Unfortunately no other backup product that > >> I know of implements the same backup strategy. As a side effect, there > >> is no real competition in this space and the licensing costs of TSM > >> aren't pretty... My current employer isn't a TSM shop and as I'm not > >> exactly thrilled with our current backup solution, I'm looking at > >> affordable TSM alternatives but it appears that there just aren't any. > >> > >> I hoped that Bacula's new "basejob" deduplication feature would start > >> offering something in this direction (as files in a basejob are only > >> backed up once), but now that I've read a bit more about it, it doesn't > >> seem to do what I hoped for. :-( > >> > >> What could be the reason no other companies or open source projects go > >> in this direction? There are great open source databases, there are > >> great open source backup projects, but there are none which attempt to > >> forge these technologies into an "always incremental" backup product > >> (or. "enterprise class data management system" as some prefer to call > >> it...). > > > > Bacula has had "progressive incremental or always incremental" since the > > very beginning of the project. It is however, in my opinion, a feature > > that had certain disadvantages tjat TSM doesn't mention much until a two > > recent Bacula features called VirtualFull and Accourate We just do not > > advertise it as much as TSM does, but it is there. Do a full and then > > incrementals, and when Bacula does a restore, it reads and restores only > > the last incremental written for each file. The downside of this is that > > if you don't have a VirtualFull+Accurate, you may end up with missing > > files and/or a very large number of volumes needed to do a restore. > > > > Base Job deduplication is yet another feature (Bacula only as far as I > > can tell) that can drastically reduce the amount of data transferred for > > a backup -- particularly for a Full backup. > > > > Best regards, > > > > Kern > > > >> Best regards, > >> > >> Pascal > >> > >> P.S. The following document is a great introduction to TSM concepts: > >> http://www.redbooks.ibm.com/redpapers/pdfs/redp0044.pdf a ------------------------------------------------------------------------------ The Planet: dedicated and managed hosting, cloud storage, colocation Stay online with enterprise data centers and the best network in the business Choose flexible plans and management services without long-term contracts Personal 24x7 support from experience hosting pros just a phone call away. http://p.sf.net/sfu/theplanet-com _______________________________________________ Bacula-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/bacula-devel
