On Sunday 30 March 2003 8:57 am, Dieter Maurer wrote:
sean.upton@uniontrib.com wrote at 2003-3-28 14:18 -0800:
Copying a FileStorage while transactions are being appended to the end of it potentially means that the copy completes with before the transaction commit is totally flushed to the file, so there is always the possibility that your backup is going to need to have half-written transactions manually truncated to be used on either a replica or a new Zope/ZSS instance; this isn't that big of a deal ....
When I understand this right, then this is done automatically when the "FileStorage" is opened.
I think that is correct - Ive never needed this *manual* process after a correct backup/restore cycle of FileStorage This truncating process might be automatic, however it is slow because it effectively needs to regenerate data.fs.index. It is impossible for a backup of a live FileStorage to atomically backup this file. The process of recreating the index needs to read the entire data.fs file into memory from start to end. This process would be needed in between any attempted incremental backup or incremental replication cycle. In comparison DirectoryStorage is close to maximally efficient at incremental backups and replications. DirectoryStorage's efficiency with incremental operations comes at a cost; it is slower than FileStorage to make or restore a full backup. Creating all those tiny files in a filesystem is equivalent to recreating data.fs.index, but slower. (provided data.fs.index fits in memory of course. FileStorage is terminally slow once you push it into swap.) -- Toby Dickenson http://www.geminidataloggers.com/people/tdickenson