Special SSD Defrag Mode

[Super Fast]

With the recommended way to "defrag" a USB drive being to cut & paste the items to the computer, then back again, I have been wondering about implementing a special way to defrag SSD drives.

 

Perhaps a sort of cut & paste mode that will allow Defraggler to arrange the blocks in a contiguous manner without wasting as many write cycles?

 

This would probably be more beneficial to SSD drives, would it not?

 

* Could make a requirement to have at least 1 GB free. I thought about 10% free, but on a 3 TB drive, that would be 300 GB... So 1 GB may be more feasible.

[Augeas]

It's easy to forget (or never to know) that the representation of clusters that defraggers show is taken from the file system, not from the disk (hdd or ssd). A storage device knows nothing about files, it just writes or reads sectors or pages when it's told to.

 

Defraggers consolidate the multiple dataruns of each fragmented file in the MFT (in NTFS) into one contiguous run, and almost as a by-product the clusters are moved on the disk accordingly. The nice picture of blocks you see is taken from the MFT and/or the cluster bitmap.

 

Once an SSD has been used there is no correspondence between the logical structure of the clusters seen by the file system - and the user - and the physical layout of the pages on the device. So contiguous has no real meaning at the device level. The mapping is done, I believe, by the Flash Translation Layer in the device controller. Users cannot see beyond the file system view.

 

It would be nice to have a logical defragger for SSD's that consolidated the dataruns in the MFT but just updated the logical to physical mapping tables on the device, but that is probably whimsy at the moment.

[Super Fast]

One thing I always like about your posts, is your detailed responses. Usually, they greatly clear up things for me.

[Augeas]

Usually?