Date: Mon, 15 Oct 2007 01:41:31 -0500 From: "Rick C. Petty" <rick-freebsd@kiwi-computer.com> To: Juri Mianovich <juri_mian@yahoo.com> Cc: freebsd-fs@freebsd.org Subject: Re: comparing two filesystems with different newfs values ? Message-ID: <20071015064131.GA44208@keira.kiwi-computer.com> In-Reply-To: <759671.62342.qm@web45603.mail.sp1.yahoo.com> References: <759671.62342.qm@web45603.mail.sp1.yahoo.com>
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On Sun, Oct 14, 2007 at 10:01:51PM -0700, Juri Mianovich wrote: > > So, doing the math, the total space used of the three > filesystems is: 3982780996 > > (roughly 4 TB) > > I just created a new filesystem on system B, where I > used newfs on raw disk to create a SINGLE large >2TB > partition. The newfs command I used was: > > newfs -i 32768 -U /dev/aacd1 > > I then used rsync to transfer ALL of the data from the Which rsync options did you use? > old system to the new system. Now that I am done, and > I have re-run rsync several times to be sure that all > of the data is in place on the new system, the space How many times is "several"? And why do you need to run it several times? > used on the new system is: > > 3552249780 > > That's a difference of almost .5 TB ... and > furthermore, I would think having less dense inodes > would actually _increase_ the effective space that all > those files take up, not _decrease_ it ... Why would you think that? By "less dense" I'm assuming you mean lowering the inode density value (via the -i newfs option). But lowering it from what? If you don't specify the option, you will get more inodes. Specifying the option generally lowers the total number of inodes allocated. Using a larger number will decrease the total number of inodes. In your case, you actually increased the inode density (the default is about 8192). Therefore, you've reduced the number of inodes available by about one quarter. Also the number of inodes has nothing to do with how much space should be taken up by a given set of files-- just how much space is available on the device for storing data. > So is this expected ? No idea. You haven't provided enough information. I'll assume your "used space" number comes from df(1). Do you have any sparse files? I typically use "rsync -avHSP" which copies sparse files without allocating blocks unnecessarily. Another thing, if you have a lot of directories and those directories were large at one time but are now less full, copying the files will actually allocate fewer blocks for those directories. I've often seen a minor discrepency due to that. > Does it have something to do > with moving the data from three partitions to one ? Only if you copied files ontop of each other, but that's not likely the case if you've repeated the rsync and it didn't transfer files. > The bottom line is, I want to be SURE that all of the > data is transferred before I scrap system A ... rsync > is telling me all the data is there, because when I > re-run it, nothing new gets transferred ... but I There you go. That's your proof. Assuming you use the same rsync command that I do. -- Rick C. Petty
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