G
gus
Guest
some further thought - It makes sense that the backup would slow down when the in-memory filesystem cache was exhausted. But that should be so whether we are writing to a new file or an existing one. - Writing over an existing file should be /faster/ since disk space has alreay been allocated. - If backup blocks are not a multiple of the file system blocksize (and I do not recall what the backup blocksize is) then that could introduce an inefficiency in writing. If a backup block were say 3 and a half filesystem blocks, then writing a backup block would overwrite 3 filesystem blocks and update one, which requires reading it and pasting new data over half of it. That might require waiting for a full rotation of the disk platter. When writing a new file, no reading is necessary. Maybe that is the cause.
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