Hi all! I've got a question about rsync using the MD5 algorithm. I know that rsync makes blocks of a file and then compares the checksums of each block. If the checksum is unequal the block is tranfered. Otherwise it could be that the checksum is the same but the block is different. Therefor rsync uses a 128 BIT MD5 algorithm. Now, at what filesize is it better to check the whole file with MD5 and when its faster just to copy the file? Is there a formula, table or diagram which it shows? (I think it depends on the Hardware!) Unfortunately I didn't find anything. Thanks a lot. Spanockel _______________________________________________________________________ T?glich 1.000.000 Euro gewinnen! Jetzt kostenlos WEB.DE MillionenKlick spielen! millionenklick.web.de/?mc=mail@footer.mklick@home
That decision obviously depends on processing power and network capacity available. A recent thread on Slashdot (tech.slashdot.org/tech/08/12/14/162235.shtml) mentioned this research which might give more insight: cs.cmu.edu/~dga/papers/dsync-usenix2008-abstract.html And btw, I though rsync used MD4, not MD5. Jeroen van der Vegt System designer ________________________________ Technolution B.V. Telephone: +31(0)182 59 40 00 Fax: +31(0)182 53 97 36 E-mail: Jeroen.van.der.Vegt@technolution.eu Visit us at: technolution.eu Mailing address: P.O. Box 2013 - 2800 BD Gouda - The Netherlands Address: Zuidelijk Halfrond 1 - 2801 DD Gouda - The Netherlands ________________________________ This e-mail is intended exclusively for the addressee(s), and may not be passed on to, or made available for use by any person other than the addressee(s). Technolution B.V. rules out any and every liability resulting from any electronic transmission.> -----Original Message----- > From: rsync-bounces+jeroen.van.der.vegt=technolution.nl@lists.samba.org > [mailto:rsync-bounces+jeroen.van.der.vegt=technolution.nl@lists.samba.org] > On Behalf Of David de Lama > Sent: dinsdag 16 december 2008 14:34 > To: rsync@lists.samba.org > Subject: rsync and MD5 > > Hi all! > > I've got a question about rsync using the MD5 algorithm. > > I know that rsync makes blocks of a file and then compares the checksums > of each block. > If the checksum is unequal the block is tranfered. > Otherwise it could be that the checksum is the same but the block is > different. > Therefor rsync uses a 128 BIT MD5 algorithm. > > Now, at what filesize is it better to check the whole file with MD5 and > when its faster just to copy the file? > Is there a formula, table or diagram which it shows? (I think it depends > on the Hardware!) > Unfortunately I didn't find anything. > > Thanks a lot. > > Spanockel > _______________________________________________________________________ > T?glich 1.000.000 Euro gewinnen! Jetzt kostenlos WEB.DE MillionenKlick > spielen! millionenklick.web.de/?mc=mail@footer.mklick@home > > -- > Please use reply-all for most replies to avoid omitting the mailing list. > To unsubscribe or change options: > lists.samba.org/mailman/listinfo/rsync > Before posting, read: catb.org/~esr/faqs/smart-questions.html
That decision obviously depends on processing power and network capacity available. A recent thread on Slashdot (tech.slashdot.org/tech/08/12/14/162235.shtml) mentioned this research which might give more insight: cs.cmu.edu/~dga/papers/dsync-usenix2008-abstract.html And btw, I though rsync used MD4, not MD5. Jeroen van der Vegt System designer ________________________________ Ok, i will check the two links, thanks! "Version 30 of the protocol (released with rsync version 3.0.0) now uses MD5 hashes rather than MD4." rsync.samba.org/ftp/rsync/src/rsync-3.0.0-NEWS David ____________________________________________________________________ Psssst! Schon vom neuen WEB.DE MultiMessenger geh?rt? Der kann`s mit allen: produkte.web.de/messenger/?did=3123