On Wed, 2011-01-19 at 17:26 +0000, Tyler J. Wagner wrote: > On Wed, 2011-01-19 at 16:34 +0000, Ed McDonagh wrote: > > Isn't someone going to mention checksum caching to save processing on > > the backup server side? > > Thanks for doing so. Perhaps you could explain? > > Regards, > Tyler >
Not without looking it up, when there are far more authoritative people on this list who can trot it off without thinking! However: http://backuppc.sourceforge.net/faq/BackupPC.html#rsync_checksum_caching Basically add --checksum-seed=32761 to both the RsyncArgs and the RsyncRestoreArgs. Without this option, each file on the backuppc side needs to be uncompressed and the checksums are calculated to send to the client for comparison. Therefore there is a lot of disk i/o and processor use without actually transferring any file data because nothing has changed. With this option, the checksums are cached on the server side, thus removing the disk i/o and processing. This still needs to take place on the client side, but without the decompression step. There is also a $Conf{RsyncCsumCacheVerifyProb} setting with a default value of 0.01, which means that 1% of the time the cache checksums are verified. Hope that helps. ######################################################################### Attention: This e-mail and any attachment is for authorised use by the intended recipient(s) only. It may contain proprietary, confidential and/or privileged information and should not be copied, disclosed, distributed, retained or used by any other party. If you are not an intended recipient please notify the sender immediately and delete this e-mail (including attachments and copies). The statements and opinions expressed in this e-mail are those of the author and do not necessarily reflect those of the Royal Marsden NHS Foundation Trust. The Trust does not take any responsibility for the statements and opinions of the author. Website: http://www.royalmarsden.nhs.uk ######################################################################### ------------------------------------------------------------------------------ Protect Your Site and Customers from Malware Attacks Learn about various malware tactics and how to avoid them. Understand malware threats, the impact they can have on your business, and how you can protect your company and customers by using code signing. http://p.sf.net/sfu/oracle-sfdevnl _______________________________________________ BackupPC-users mailing list [email protected] List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/
