I just tried to partition my Patriot Xporter XT thumb drive, and I found that although Disk Utility shows its capacity as 8.02 GB, I can only create volumes totaling 7.67 GB; it seems to have somehow lost 350 MB of storage space that was heretofore available.

I know that thumb drives can be compromised by writing to the same "blocks" too many times, but even without knowing my drive's parameters I think I can safely say that I'm nowhere near in danger of that.

Is there any explanation for such a loss, and can the drive be trusted?

(I remember the thing giving me fits the last time I partitioned it...not accepting the partition sizes I selected until after any number of tries.)

Thanks.

Its capacity is one thing, the usable space another.
If you check your main computer's hard drive you'll note that the 'discrepancy' exists there too. The amount of the discrepancy depends on how it's formatted (or so I'm thinkin').

There is always space consumed by "overhead"; space needed for directories, organizational stuff and "medium bookkeeping".

I don't believe I have ever had a disc or disk that made the specified capacity completely available for use.

I'd love to be able to say that you and grelber are on the mark, but, sorry, nope; you're correct as respects drives in general, but not as respects my specific current circumstances.

First, and as I mentioned in my OP, close to 100% of those missing 350 MB were recognized when I initially partitioned the drive.

And second, here's a comparison of my four storage devices:

1. Internal Toshiba:                    500.11 GB        Total capacity
                                                 499.37             Capacity of 4 partitions
                                                    0.74              Overhead = 0.15%

2. External WD Scorpion Blue:     500.11 GB         Total capacity
                                                 499.77              Capacity of 2 partitions
                                                     0.34              Overhead = 0.07%

3. Sony thumb drive:        1,002,438,656 Bytes     Total capacity
                                       1,002,397,696             Capacity of 1 partition (Exact same for 2)
                                                  40,960              Overhead = 0.004%

4. Patriot Xporter XT thumb drive:  8.02 GB         Total capacity (*)
                                                     7.54              Capacity of 2 partitions (7.67 last night)
                                                     0.48              Overhead = 6.0%

(*) During the partitioning process, DU showed that 8.02 GB was available but delivered 7.67 for 1 partition, 7.54 for 2, and 7.41 for 3 (at which point I quit trying).

The Patriot's overhead % is clearly disproportionate, and it could not have supported its high price, would not have garnered its excellent reviews, if that % were default. (Edit: It would never have been marketed if its default overhead % was 6%.)

I'm afraid my expensive drive has morphed into expensive trash…not even a paperweight…too light.

(The drive is 4 years 3 months old, but I've got no idea what "normal" life expectancies are.)

I'm just curious, did you ever try to format the drive as one partition? Any change then? Also, and perhaps more interestingly, did you check for contents of the drive with a utility like Whatsize, GrandPerspective or some such?

PS, I briefly considered the difference between decimal and digital byte prefixes (GiB vs. GB) and the numerical difference that might cause, but the implied inconsistent use of those prefixes makes that seem unlikely, and besides, the numbers don't match.

> I'm afraid my expensive drive has morphed into expensive trash

If you're going to throw it out, I'll send you my address. My car stereo reads mp3 files on usb sticks, and I can fit a lot of music on 7.5 Gb…

I'll wait a bit to see if I get a reassuring response, but if not, it's yours. I simply can't trust it as an emergency/travel boot drive any more.

(Just be sure that your music is backed up. )

It definitely seems that normal partitioning and directory overhead should not consume 350 MB on an 8 GB drive.

Patriot flash drives typically have a 5-year warranty. Have you tried calling tech support?

Wow! Thanks for bringing that to my attention. (I'm shocked to find that I didn't save the drive's warrantee info [although I do have my purchase receipt].)

The successor product to my drive has a five year warrantee, so perhaps mine also does; I'll contact Patriot tech-support and report back.

I think
answers your question. (I just duplicated those results and, in addition, found that 4 & 5 partitions --> 7.26 GB, 6 --> 7.14, and 8 & 10 --> 7.80 [Figure that out!].)

DU showed this prior to setting up a single partition and this afterwards. (What does "Size: 7.67 GB/Available space: 2.27 GB" [in the "afterwards" shot] mean?)

Good thought about Grand Perspective! This is what it showed. (What's that 7.14 GB* all about?)

Wow! Confusinger and confusinger!!!

* Edit: I decided to throw DiskWarrior at the drive with absolutely no expectations of its accomplishing anything, and it didn't, but it did return this. Got me beat!

Wow! Talk about customer service.

I e-mailed Patriot, explained my issue, and linked them to this thread, and I received a response linking me to a low level format/reset tool that could be run only from a Windows-based PC.

I replied that I could not gain access to a PC without putting someone to an immense amount of trouble, and I was linked to and instructed on how to use the Patriot RMA process...28 minutes from start to finish.

Sorry, Roger.

Ah well!

Glad it's sorted for you, Artie.

Thanks, Roger.

I really owe it all to tacit for bringing up the 5 year warrantee. (I'm still kicking myself for not having noted it.)

Congratulations to you (and tacit) for that 'mission accomplished'!

I realize it's moot now, but for future reference (when an RMA might not be forthcoming), how about emulation/virtualization?

Uhhh... "emulation/virtualization"?

Oops! I probably should have added: ...of Windows.

Oh...got it!

Well, I think "I don't know anybody who's running parallel systems" answers your question.

Edit: And if you're wondering whether I asked Patriot about it, the answer is "No".

Because I was fairly certain you hadn't, I mentioned it for a future occasion where emulation/virtualization would be an alternative. It also helps to know that there are (more or less) free options.

Thanks for the update. With hindsight, I vaguely recall other Windows issues like this with emulation/virtualization. That said, and while your post implies the answer, I'm curious to know if that applies to Bootcamp too: was there any explicit mention of that?

My quote is the entire text of the e-mail...a direct response to my question, i.e. "...I'd like to be clear about whether that EXCLUDES Macs running Windows environments". (If not asking specifically about Bootcamp made my question incomplete, I'll ask again.)

Thanks, but it's not worth the effort, given the specificity of the issue. As I said, I was just curious, it's not as if I'm likely to run into the problem.

I suspect that Patriot's response is all-inclusive; there's no reason to not mention an exception, particularly one that could save them money.

As it turns out, the important part of this thread was tacit's mention of Patriot's (I think it's unusual.) 5 year warrantee.

Most likely, it would work in BootCamp, because in BootCamp yu're basically running a high-end Ultrabook or desktop as far as the operating system is concerned.

I would expect it to work in BootCamp but not Parallels (or some other VM). In a VM, the hardware is abstracted; when a program tries to do low-level device/hardware stuff, it's not aware that the VM is in the way. If their tool does low-level hardware I/O, which it likely does, it would almost certainly not work in a VM environment, even if it did work in BootCamp.

Your thoughts pretty much describe why I asked Artie for confirmation about Bootcamp. Still, the issue is rather academic to me, as I'm not likely to find myself in a position in which I might have to resort to the option.

Interesting. Thanks for the follow up, I guess that clinches it.

in addition to the overhead, there's the matter of units. Naturally manufacturers will take every step possible to make it look like you're getting more than you are. In this case, computers use base 2 for most everything at low level, and so storage is addressed in binary also. So 2, 4, 8, 16... etc, and handily passes by 1024, which is pretty close to 1000. So 1024 bytes is a kilobyte, even though 1000 is a kilo. 1024 squared is a MB, but is 1048576 bytes.

When manufacturing storage, there's a certain amount of overhead required. Places to store remaps for instance. You might want to be able to remap 2% of the blocks on the drive if they fail. And you have to store the table somewhere. Rather than go to the added expense of adding a second storage, they nibble into the space you thought you were getting. So they "say" it's an 8GB flash drive. But it's not 8 "gigabytes". It's 8 million bytes. (look for the fine print on the package, it's there) 8GB is actually over 8.5 billion bytes. The flash storage has all 8.5 million bytes of space, but you can't use it all, you only get a shade over 8 billion to use, the controller hides the rest away for its own use. But they don't want to say you are getting 7.44GB, so they say 8gb but they mean 8 billion bytes, about 7.4 GB.

But they probably have to. Consumers are, if nothing else, predictable. The same product that sells for $90 will sell a lot better at $89.95. If one flash says it's 7.4 and the other says it's 8 for the same price, you'll probably buy the 8 even though they're the same. So since everyone does it, everyone has to do it. That's just how marketing works. It's a moral "race to the bottom".

As of Snow Leopard, FInder has started reporting sizes in kilos. Get Info on my hard drive shows capacity is 749.81GB. In terminal, diskutil info /dev/disk0 even gives:

Total Size: 750.2 GB (750156374016 Bytes) (exactly 1465149168 512-Byte-Blocks)

750156374016/1024/1024/1024 is about 698, and that's what 10.5 would have reported for disk capacity, 698GB. But people like to see the bigger number. I don't know why Apple decided to change. Maybe they got too many complaints from people about "missing space" on their hard drives, as reported by Finder and Disk Utility.

1000/1024 is about 97.5%. But when you do that three times (kb, mb, gb) it's about 93%, you lose about 6-7 percent due to math.

The much less informative tiger diskutil reports this for a "250 gb" hard drive:

Total Size: 233.8 GB

less informative, but MORE honest. 233GB / .93 is, as expected, 250 billion bytes.

Then we get into "blocksizes" which are a whole 'nother critter. The hard drive can't store a single byte, it has to reserve whole blocks at a time. If the blocks are 512 bytes, then a one character file will take 512 bytes. A 511 and a 512 byte document will take 512 bytes to store, but add one more character and the file now requires 1024 bytes to save. This doesn't look like much, but it adds up. On the average, every file wastes half a block of space. If you have 500,000 files on your boot drive, thats over 120MB. Get Info in Finder adds file bytes, NOT block bytes, so you usually don't see it.

You'll understand this issue gets worse if the block size is bigger, since the waste is (number of files) x (block size / 2). Flash drives, due to their design, write in much larger blocks, to speed up the write process and to extend their useful lifetime. 32k or 128k may be a block size for a flash drive. 128k block size storage wastes an average of 64k per file saved to it. That adds up really fast. And the irony is, those are the smaller drives. So saving to them means your overhead is much higher, and your usable space to begin with was much lower.

Your explanation of the "differences" in HDD sizes is appreciated, but your point about block sizes was the real eye-opener for me; as obvious as it is, it kinda flies under the radar.

Thanks.

As I recall, OS 9 allowed for user-setting of block size in HFS+; I set mine for 4KB (smallest option). I've yet to see the option for that in OS X.