Hi Oliver, 2005/6/22, Oliver Fromme <[EMAIL PROTECTED]>: > Michael Schuh <[EMAIL PROTECTED]> wrote: > > now i have another question, if i use the same Os in 2 versions > > (RELENG_4, RELENG_5) can i hope that the tests are made on the same > > part of disk? > > <yoda> > Hope you always can. But rely on it you should not. > </yoda> > ;-) > That's right. :-D
> > or in other words can an dd on the two OS' es so much different > > because they use an > > totally other part of disk? I think no, the strategie from dd under > > one OS should not be changed if the OS-Version has changed. > > It's not the dd which decides where to put the file, it's > the filesystem code. And yes, there can be differences > between RELENG_4 and RELENG_5. In particular, in RELENG_5 > you have UFS2, not the old UFS. There have always been > changes to the FS code, for example I remember that the > allocation of directories has changed some time ago to > improve metadata performance for large trees (known as > "dirpref"). > > As I said: The only way to make sure you hit the same > physical place on the disk is to use a raw partition, not > a file on some filesystem. > Yes i have that understand. And that was the reason why i make in future these tests new with an raw-partition on the same part of disk. so that i never must hope, so i become knowledge and i know the facts :-D > Note that even small differences in the placement of the > file can have a noticeable effect on the speed. Apart > from the speed differences of the disk cylinders, it can > also happen that the file is allocated in a non-contiguous > way, especially if it is large and the filesystem already > contains a lot of files, and/or had a lot of write+delete > operations previously (i.e. causing fragmentation). > yes this is also clear for me, but in my case, it was only a small disk (8GB) and it has only the OS, nothing more, nothing less. And as i made these tests, i have all the performance for me and my OS. *grrrrr* i be the master of disaster.......... *lol* We should have all more humor.......the life it's more funny...... > > the part with serial IO related to database-performance have i > > understand, but i quests me have the others understand > > my meanings? > i must hope so :-D, i can not sure > That I don't know. > > Best regards > Oliver > > -- > Oliver Fromme, secnetix GmbH & Co KG, Oettingenstr. 2, 80538 München > Any opinions expressed in this message may be personal to the author > and may not necessarily reflect the opinions of secnetix in any way. > > "anyone new to programming should be kept as far from C++ as > possible; actually showing the stuff should be considered a > criminal offence" -- Jacek Generowicz > thank you for your suggestions best regards Michael Schuh _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[EMAIL PROTECTED]"
