1) If you run MagicRAR Drive Press on Windows XP, or for example Server 2003, you will see that there is no difference in free space gains between using MagicRAR Drive Press and Windows itself to compress the drive. This is because this bug does not exist on NT 5.x OS's. It was introduced for the first time in Windows Vista, and has remained on all Windows versions (including Server editions) since.
As you have correctly discovered, a big part of this difference (though not all
) is explained by the Windows shell failing to temporarily acquire and then restore permissions to protected file system areas. This is a bona-fide bug, because as you have seen for yourself, compressing these additional files is completely safe, and was already a matter of fact on older Windows versions. There is nothing preventing Windows Explorer from doing exactly what MagicRAR Drive Press is doing for you here; in fact that is exactly what it should have been doing
in the first place.
2&3) You would need an SSD to see this for yourself, but no - these claims of yours are still false
. Because most modern SSDs have an incredibly high number of IOPS, and because NTFS compression has very low CPU overhead as you have correctly determined, it is possible to dramatically accelerate the conversion process of an entire hard disk by maxing out the worker threads available.
In my experience, one CPU core (even if it is only an HT core) can handle two NTFS compression worker threads. So this is why the MagicRAR Drive Press Options Window offers to create up to double the number of worker threads as you have CPU cores available. Whether or not you use all of these depends on how fast your hard drive is. I would not recommend more than two-three threads with a mechanical drive, based on how fast it is (say 1 thread
for 5400 rpm
or slower; 2 for 7200 rpm
or slower, and 3
if you have a 10k rpm
drive - maybe 4
if you have a 15k rpm
With an SSD, you can go really crazy though! For example Intel 320 series 600 GB SATA II SSDs seem to be able to handle 12 threads just fine. Now, even with Windows having a lot less files to compress, you can imagine that with 12 times the firepower, MagicRAR Drive Press just comes out on top of the speed race: Assume that Windows has about 1/3rd the job to do (roughly accurate, per our claim that MagicRAR Drive Press triples Windows compression
). If MagicRAR Drive Press has to do 3 times more work, but can do it 12 times faster; this still works out to about 4 times faster globally. So this is a happy case of you having your cake and eating it too: You save three times more space, and four times faster at that!
Does that sound like well built software to you?
again. NTFS compression does increase fragmentation on hard drives, and this has nothing to do with MagicRAR Drive Press, since it is an innate disadvantage (and quite probably the only one) of using NTFS compression. However, a fragmented hard drive has absolutely zero impact on an SSDs performance. Fragmentation slows down your read/write speeds, because the drive head is constantly waiting for the platter to spin to all kinds of different places when reading/writing data. It is exactly this overhead that SSDs do not have, and that is why they feel so fast.
Because an SSD can read from/write to all parts of the drive at the same time (think of a hard disk platter rotating at infinite speed), that is why fragmentation is of absolutely no consequence for SSDs - be it NTFS compression induced, or the "normal" fragmentation that happens on NTFS inevitably. There is no delay, because all areas of disk are equally accessible at all times.
In fact, this random access speed boost is the main reason why SSDs feel so fast. If you compare sequential access speeds between SSDs and mechanical drives, they're not too far apart. There's certainly no 10-20 times difference in those peak read speeds. It's only when you start comparing random access speeds that SSDs are many orders of magnitudes faster than mechanical drives. That is the main reason why its such a thrill to use them - you can keep throwing more and more work at the computer, and it just won't slow down.
A few closing points:
a. Do NOT
attempt to manually acquire file permissions just to be able to compress them. Doing this will create a huge security hole on your system (one that MagicRAR Drive Press does not create, because it restores all permissions as has been confirmed in this third party report). And because virtually all areas of your system folders have unique permissions, it will be near impossible for you to manually restore permissions correctly. You may find yourself unable to install software on your computer, for example, if you mix up permissions during the restore phase.
Again, this is why properly speaking, this is considered to be a bug in Windows - one that is practically impossible to workaround manually without third party software that does the job automatically.
b. There will always be some files/folders that would be locked by the system/applications, and as such incompressible. If there is demand for it, we could also automate the conversion of those parts by building a boot time version of MagicRAR Drive Press - however, in my research, the additional space savings would be negligible.
So while the MagicRAR Drive Press Challenge technically remains unmet, I would be delighted to give f0dder a free key for the full MagicRAR 8.0 product, in appreciation of his time
. It's the least I could do to thank for an open mind