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[iparout]

Hi.

I just purchased the DNS-320, installed firmware 2.02 and a Western Digital WD30EZRX 3Tb drive.After installing it as a single drive, although the web interface (System status - Hard drive info) indicates a size of 3000 GB, storage status on the web interface shows a total of 2748.71 GB total capacity. Why is there a difference in those numbers and is there anything to do to make the rest of the HDD's space available ?

Thanks !

[cable2]

Hi,
I don't think you are going to get any additional space.  I used 3TB Hitachi drives and get only 2748 MB for those.  First off, you never get the advertized capacity because the drive manufactures use a measurement which makes it seem like the drive is larger than what is actually able to use usually by about 7%.  Then you add in the small amount of space used by the device itself for admin or whatever.  If you double check the figures on any windows machine you will problably find the same discrepancy.  They call this marketing....some people call it something else.  Sorry for the disapointment.  Have a good day.

[JavaLawyer]

The actual available usable space for a non-RAID formatted HDD is an artifact of how the HDD industry defines what a TB really is. It's all about the math. From a computer science perspective (and in engineering terms), 1 TB = 1024 GB, 1 GB = 1024 MB, and 1 MB = 1024 KB. It's industry standard practice to round down and call 1 TB = 1000 GB, 1 GB = 1000 MB, etc. This simplified math results in a compounded storage loss of roughly 2.3% for each level of conversion as you scale up from the KB to TB range. Due to this differential, the net result for a 3TB HDD is total loss roughly around what you're seeing as your available storage space. After you factor in the overhead for indexing/addressing and reserved memory to compensate for bad blocks, your available storage space is dead-on.

The difference between advertised and usable storage was a sticking point around 20 years ago when storage was very expensive and consumers felt cheated by (as cable2 pointed out), creative marketing.

[iparout]

I see... Thanks a lot for the insight, guys !

[albuemil]

As JavaLawyer said, 1GB defined by the HDD manufacturers doesn't equal 1GB defined by the OS, also, the NAS makes a few partitions where it holds its data and swap partition.
This partitions are not accessible, for me it was 3 hidden partitions totaling 2Gb of space.

Another place where you will "loose" some space is the way the file system works, the file system (Ext3 in this case) will occupy some space for the folder structure too, but that usually is small enough that it doesn't matter (we're talking about a few tens or hundred Mb, not Gb).

All of the above explain the difference between the "hard disk size" and the "available space".