Computer related questions

[Dumbledork]

I have a question about two of my hard drives. Both are WD Elements 2TB and both contain exactly the same files (one is a backup drive) which I uploaded at the same time. The problem is that one of them apparently contains 100 Gb more data than the other one. How is that possible?

[Neko-]

Are you copying data over between the two, or using them in a mirrored RAID set?

I'm guessing the former, since the mirror set would just show one drive, and let the RAID controller sort it all out (which is what mine does).

If you do copy over data from one to the other, do you also delete stuff prior to copying? In which case some old data might be present in the folders abd taking up space. Also, verify your pagefile. Not stored on one of the two drives? Partitions are setup the same on both drives (not like one partition is bigger then the other)? And lastly... You may have previous versions enabled on the drive, in which case the OS may be storing snapshots of data for a revert to previous versions. http://windows.microsoft.com/en-au/wind ... =windows-7

[Dumbledork]

Partitions are the same. All the files copied to the two drives come from my C: drive. No idea what a RAID set is. Both drives contain exactly the same amount of files. I verified it on both drives.

[Ellen Kuhfeld]

It's unlikely, but perhaps the drives are formatted differently. If they were, depending on the size of files you have (and with that large a drive I'd imagine they're video) they might pack more efficiently into one size of sector than another. This could happen if, for instance, one drive were in your computer and the other set up as a USB drive.

[Dumbledork]

Nope. Both are exactly th same. Bought the same day. Used for the first time the same day. Both are external.

[Neko-]

Using TreeSize as a utility doesn't help you find the extra used space?

http://www.jam-software.com/treesize_free/

[PCHeintz72]

treesize free would not help in a situation like that...

HOWEVER, a drive and directory comparison utility like scooter software beyond compare would work nearly instantly.

Beyond compare is my preferred choice, and comes as a trial period for free.

Install it, then tell it folder compare, then tell it one drive letter on the right, the other on the left, and tell it to compare and show differences and expand the folders. it will tell you every file different between the two drives.

I'm a registered user of beyond compare and been using it for some 15 years, started at work, but use it at home for network syncups.

[Spica75]

Nope. Both are exactly th same. Bought the same day. Used for the first time the same day. Both are external.

Does both drives have the same total drive space? If one drive is going bad, it may already have run out of spare sectors for remapping, and at that point disk size total will start to shrink(which could make it look like that drive has more data because it has less free space).

So, question is if it´s less free space or more data.

If it IS more data despite same number of files, you can check directory by directory to see if they are identical in size.

No idea what a RAID set is.

You don´t use it, so no need to worry about it. FYI, RAID is when you cluster 2 or more HDDs together, usually either to get redundancy or performance.

RAID 0, striping, works by having the RAID controller "zig-zag" between drives that it reads or writes from, as the bus speeds are vastly higher than that of HDDs, you can get increased performance by having 2 or more drives working constantly, working with half(or less) of the data each.

RAID 1, mirroring, is simple, you have at least 2 drives, and everything you do will be written identically to both drives. A good RAID controller will also allow some performance benefits from this by reading different parts of data from both(all) drives at the same time, getting the advantage of RAID 0 for reading(but not for writing).

RAID 5, 3 (or more drives), writes to the drives sequentially, half data to drive 1, half to drive 2, then parity on drive 3, next block is shifted 1 step. As long as only 1 drive fails, a RAID 5 set can always recreate all data on the disks.

Those 3 are the common ones together with RAID 10(referring to RAID 1 and 0 together).

[PCHeintz72]

Spicca75 hit the big ones.

There are plenty of variations out there on how to securely store data.

Most of it the average person has no need to know or care about.

RAID 5 can work with a number of drives

I myself use 2 individual stand alone office grade Synology (Diskstation 409slim and 411slim) RAID 5 units each with built in custom Linux core OS and 4 drives each all formatted to EXT4, the one uses Samsung Spinrite drives, the other western digital black drives. Each is also set to autoscan their contents fro viruses on a regular basis, and have separate login and user rights control.

The beauty of the setups are each unit not counting the ac adapter can fit in palm of hand and is easily transportable.

On a semi-regular basis, those are in turn backed up to my HTPC units, in case they ever fail.

[Dumbledork]

Does both drives have the same total drive space?

Yes.

I'll try beyond compare and see what I get.