June 6, 201016 yr Last week I upgraded unRAID server from 4.5 to 4.5.4. I also did a full parity check on the system and all is well. I now have a six disk unRAID 4.5.4 PRO array consisting of six 2TB WD EADS drives. See attached "screenshot.png". I don't use unRAID server "shares" to move data files from my workstation to unRAID server; instead, I copy data from my Ubuntu 10.04 workstation directly to the unRAID disk I want the data saved to with path command: smb://192.168.0.10/disk1/........ using Nautilus. I understand that Reiser FS is supposed to be more efficient than ext3/4, however, I am confused about a situation I just noticed concerning the number of files and remaining free space on "disk 1" of unRAID server vs. the same exact files (in number and size) on my Ubuntu workstation, using the same make and model WD 2TB hard disk formatted to the ext4 fs. To be clear, my Ubuntu 2TB drive (ext4 fs) is an exact mirror of what is contained on unRAID "disk1" (Reiser fs), the only difference is the filesystem. My unRAID WD 2TB disk1 shows over 158GB free space! However, my Ubuntu workstation's WD 2TB drive (with the identical files shows only 45.5GB free space. Why the vast discrepancy in free space between Reiser and ext4? Reiser can't be that efficient. What am I missing? Thanks for any helpful insights.
June 6, 201016 yr Yes, it can, and it depends on the sizes of the files. One giant 1.9TB file? No, there won't be that much difference. But for a bunch of small files, you betcha.
June 6, 201016 yr Author BubbaQ, Thanks for the reply, but as I mentioned the files are identical on both systems (Ubuntu & UnRAID), therefore, your examples wouldn't exactly apply IMO. I am trying to understand why the sizes are so different (158GB for unRAID vs 45GB for Ubuntu) That's almost a 3 to 1 difference. Half the files are very large and half are fairly small. I just ran "Unmenu" and performed a "disk usage check" and it says that unRAID server's "disk1" has 1.9T used which would make more sense. However, when I look at "Unmenu's" array status screen, it's not all that different from the default Limetech GUI. See screenshot2.png.
June 6, 201016 yr 1) Identical files do not use the same amount of disk space on drives formated with different filesystems.. 2) identical drives formatted with different filesystems can have vastly different amounts of free space actually available for user files.
June 6, 201016 yr Author 1) Identical files do not use the same amount of disk space on drives formated with different filesystems.. 2) identical drives formatted with different filesystems can have vastly different amounts of free space actually available for user files. I agree with both 1 and 2. I'm just having difficulty understanding a 3 to 1 difference. I know that ext3/4 most likely reserve more disk space for root/housekeeping than Reiser (although I don't know that to be a fact), so that would account for proposition "2". As for proposition "1": I appreciate that a 50KB file written to a ext4 fs might be larger or smaller than the same 50KB file written to a Reiser fs. My question is: given identical files, is it possible to know what the average % difference in stored filesizes is/will be between the two filesystems?
June 6, 201016 yr the ext filesystems use inodes and inode tables for indexing file space. In addition, there are backups and backups of the superblock. I do not think reiserfs uses or reserve inode space the same way. Probably one of the reasons you are able to recover data during an accidental destructive operation. In addition when ext2,3,4 are first created they reserve a certain percentage of file system space for the root user. When formatting with either of these, use the -m0 or -m1 to reserve a smaller portion.
June 6, 201016 yr I agree with both 1 and 2. I'm just having difficulty understanding a 3 to 1 difference. It is not a 3:1 difference. It is a 100G difference on a 2TB drive. That is a 5% difference. Take a 2TB drive and format it with one file system, and then with another. On a 2TB drive, you might have a difference of 8100GB right off the bat before you ever start saving any user files.
July 8, 201016 yr Sorry to resurrect this, but I thought of something that another user mentioned. Could it be the root-reserved space? The numbers just seemed to be too convenient: Default reserved space is 5% and ~100 gb = ~5% of a 2TB drive Remove root reserved space (unnecessary on non-OS volume): sudo tune2fs -m 0 /dev/sdf1 Obviously, replace /dev/sdf1 with the correct partition for your setup.
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