Fingerprints support

maverick · **Reply #15 on:** July 03, 2006, 07:56:23 PM

Quote from: "mastabog"

maybe you have a super machine and/or super HDD but for a 700 MB file on my P4 HT 2.4 GHz the MD5 hashing takes about 10 seconds. For slower machines it might take more.

A super machine, far from it. Actually those tests were done on a P3 900 mhz. I'll do more testing on a faster system when I get home. (btw that post of mine above was edited a few times with new results as I finished additional tests).

Regardless, it's up to rejetto to decide on what changes he would like to make, if anything.

mastabog · **Reply #16 on:** July 03, 2006, 08:50:48 PM

Quote from: "maverick"

Quote from: "mastabog"
maybe you have a super machine and/or super HDD but for a 700 MB file on my P4 HT 2.4 GHz the MD5 hashing takes about 10 seconds. For slower machines it might take more.

A super machine, far from it. Actually those tests were done on a P3 900 mhz. I'll do more testing on a faster system when I get home. (btw that post of mine above was edited a few times with new results as I finished additional tests).

Regardless, it's up to rejetto to decide on what changes he would like to make, if anything.

Read your edited post and yeah, HFS could automatically compute the MD5 hashes for small files (e.g. less than 32 MB ). Usually people check bigger files against MD5 hashes but your idea makes sense nonetheless.

This could be another global option in HFS - automatically compute MD5 hashes for files smaller than <user editable value here> MB. That would be really neat!

rejetto · **Reply #17 on:** July 04, 2006, 11:35:25 AM

it's not a matter of CPU, md5 is designed to be fast
the only bottleneck is hard disk speed.
on my laptop, most of times my hard disk stays under 10MB/s.
laptops have slow HDs.
i just tested md5sum on a 700MB file, and it took 1 minute, with speed varying from 8MB/s to 14MB/s.
i made the test while the hard disk was not busy.

Anonymous · **Reply #18 on:** July 04, 2006, 03:23:22 PM

Quote from: "rejetto"

it's not a matter of CPU, md5 is designed to be fast
the only bottleneck is hard disk speed.
on my laptop, most of times my hard disk stays under 10MB/s.
laptops have slow HDs.
i just tested md5sum on a 700MB file, and it took 1 minute, with speed varying from 8MB/s to 14MB/s.
i made the test while the hard disk was not busy.

It is fast, of course, it is just another CRC alg. However, what I said is that it is CPU intensive (a lot of CPU activity), meaning that during hashing the CPU usage of the hashing process can reach almost 100% (you can verify that with task manager).

That is not desired as it slows the other processes down hence my opinion against making HFS compute md5 hashes on the fly for all files and making it either a global strict option or a global option where the user can input a maximum file size for which the MD5 hashes should be computed automatically when added to HFS.

mastabog · **Reply #19 on:** July 04, 2006, 03:25:28 PM

Offtopic

Ack!

the board logged me out again. It was me in the post above. Have you setup the board so it expires the cookies after a number of days? My cookie for this board seems to expire after some interval ...

rejetto · **Reply #20 on:** July 04, 2006, 04:23:49 PM

i think the problem is about the change of domain (www.rejetto.com -> rejetto.com).
i have problems accessing admin panel ATM.

anyway, i don't think it is a good idea to have this feature that calculates MD5 at addition.
we can't have 2 commands, one that saves to disk and one that keeps the MD5 in memory: concerning the GUI it would be too intrusive.

mastabog · **Reply #21 on:** July 05, 2006, 09:40:58 AM

Quote from: "rejetto"

we can't have 2 commands, one that saves to disk and one that keeps the MD5 in memory: concerning the GUI it would be too intrusive.

Well, why would you want to implement two commands?

You would either save to file or to memory, but not both. I would say to save the md5 hash to file as it will be there later at subsequent launches of HFS and it wouldn't need to be computed again, unless instructed to by the user.

Quote from: "rejetto"

anyway, i don't think it is a good idea to have this feature that calculates MD5 at addition.

Please allow me to differ, I think its a great idea to have the hashes computed at addition time *provided* that there is a global option in the menu to limit the maximum file size for which the md5 hash should be automatically computed on addition. It could be by default set to a very low value (e.g. 4 MB) and the user can adjust it to his liking or enable/disable it for all files, regardless of their size.

Your call, as always, but I think it would make a great addition.

CuriousGuest · **Reply #22 on:** November 07, 2006, 01:36:24 AM

Sorry, but im interested on the advantages of the fingeprint feature...
Tell me an example plz...

rejetto · **Reply #23 on:** November 07, 2006, 02:00:31 AM

it is a way to automatically check the integrity of the file you are downloading.