Thanks for those very interesting links. At the last one, this post struck me in particular:
http://www.overclockers.com/forums/showthread.php/687139-3TB-External-hard-drive-works...=1#post6969302
That reads a lot like what I remember from that thread at Tom's Hardware I referenced earlier (wish I'd bookmarked it). A fuller explanation though, as it seems that this is not something you can do yourself by formatting/partitioning an MBR drive with 4096 sector size. So I was mistaken in my interpretation.![]()
That is, the external drive is using/reporting 4096 at the USB interface, but 512 at the internal SATA interface.
This quote (same post) also struck me as possiblyexplaining the OP's problem with some software not being able to access the drive:
"So having the USB interface present an MBR-style drive with 4KB sectors should work fine (at least as a data drive, and with software that doesn't depend upon a 512-byte sector size)..."
By extension, doesn't that also mean that with a GPT partition (4096 sector size), there would be the same problem for some software, e.g. DVDShrink? Not just with the enclosure, but any GPT partition.
[EDIT] What would happen if you took the enclosure out of the equation? I mean, pop the drive out of the enclosure and use it as an internal drive? I'm thinking if you then made two MBR partitions, the problem would be gone.
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Last edited by fritzi93; 19th Jan 2015 at 15:34.
Pull! Bang! Darn! -
@skaleton
I installed and ran the 32bit MPC-HC and got the folllowing error message on all video types. Click OK and the file plays fine. There's no problems with the X64 version. Is this error you're receiving? I suspect it's because I'm running X64 DirectX.
Your issue with your Blu-Ray player is common. Check your manual and it's likely to specify that a 2TB partition is the largest it will support. Like DB83, I always split my >2TB drives into 2TB max partitions to ensure compatibility with my media players and consistency with my backups.
As for partitioning, I highly recommend Easeus Partition Master. It's free and I've been using it for years. You can choose MBR or GPT and adjust sector size as well as multiple other options such as moving and resizing partitions.
In theory, a drive set to MBR can be larger than 2TB if the sector size is 4096, but there can only be one partition. Any additional space is inaccessible (as you've found out). Windows Disk Management won't allow >2TB partitions (even with 4K sectors) and I'm not sure EPM will either. Bottom line is if you need a larger than 2TB partition, use GPT. -
Just to confirm....
So you're saying if you divide a 4TB drive into 2 x 2TB partitions, most devices which can play video via a USB input (YVs, Bluray players etc) should then be able to see the whole drive (both partitions)?
So far I've just stuck to 2TB drives myself to avoid all this crap, and because I run XP, but it's probably approaching the stage where larger drives will provide more capacity for your dollar. Last time I looked at WD Green drives (not too long ago), the cost of a 4TB drive was only just under the cost of 2 x 2TB drives, but I imagine that's changing. -
Yes, it should be seen as two separate drives (my WDTV and Seagate Theatre sees it this way).
4TB drives are currently the best price per TB. Both Amazon and Newegg have several 4TB externals for under $130 (<$33 / TB). The lowest price 2TB external is $82 (~$41 / TB). What's really exciting (at least to me) is that 8TB externals are $300 (<$38 / TB). -
I think some of my confusion might come down to using "sectors" and "clusters" interchangeably in the past.
Now I'm looking at it like this:
A drive has a fixed sector size (traditionally 512 bytes) and the MBR is used to access those sectors so that's the reason for the 2TB limit. I was thinking something along the lines of being able to format a drive with 4k clusters and the larger cluster size would let you access the whole disc capacity, but it's obviously the sector size that puts the brakes on.
So, if a 4K drive is pretending to be a 512e drive as they currently do, the MBR is still restricted to a maximum capacity of 2TB.
GPT drives have a "Protective MBR", apparently. It's located at the same place on the drive as the MBR normally would be, and the idea is it prevents non GPT aware software from seeing the drive as empty, or unformatted. So I assume if you format a drive with a newer version of Windows and GPT, then connect it to an XP PC (via SATA) it'll show up as a GPT partition but won't be able to access it. According to this post, it'll be able to correctly identify the size though, even if it's larger than 2TB.
I think I had an idea floating around in my head that the "Protective MBR" allowed an OS such as XP to read and write to a GPT formatted drive (if it's 2TB or smaller). Kind of like having 2 file systems. Thinking about it, that doesn't seem too likely and probably means I'm somewhat silly.
So I'm still trying to understand exactly what voodoo the USB bridge is employing to keep XP happy, yet other devices (TVs, Bluray players) still give the drive the finger. If Windows could cope with 4k sectors I assume there'd be no need for any of the 512 byte emulation in the first place, so in that respect it doesn't make complete sense to me yet. I understand the USB side pretending to have 4k clusters as Windows has no problem there, but if it's pretending to have 4k sectors and a MBR to match.....
I'm not getting my head around why the drive itself needs to pretend it's not 4k (at least when connected via SATA) while for XP to see the whole capacity the USB bridge needs to pretend it is. I'm stuck in a sector emulation paradox. Am I missing something obvious? The penny won't drop.
This post indicates that XP can even format a 3TB drive as long as it's connected via USB voodoo.
And this post seems to explain what the emulation is doing but I can't get my head around it (when the drive was connected directly to the PC, Windows showed it as having 3 partitions).
"NT-based systems have been able to deal with drives with unusual (including 4KB) sector sizes at least since the mid-'90s...... So having the USB interface present an MBR-style drive with 4KB sectors should work fine..... while the firmware in the USB/SATA internal interface translates between that and whatever actual format the drive has (in this case, it looks as if it may be a GPT-style drive with 512-byte physical sectors using a single internal partition to emulate an entire 3 GB drive minus the sectors used by the GPT overhead)."
The "using a single internal partition to emulate" part is where I get lost. I don't understand how that works.
I read something similar in a few forum posts, but no real explanation. You'd assume if software wants to open/save a file, Windows would act as the go between, so as long as Windows understands the file system/cluster size, the software should be oblivious. Maybe it's not that simple though. I did read one post referring to older programs accessing drives more "directly" but nothing explaining how it all works. -
Remembered that I had a couple of spare 3TB Seagate GoFlex externals and did some testing on it as well as some other drives.
MBR
1) Easeus Partition Manager can create a >2TB MBR partition, but the smallest cluster size is 4K
2) You can also create multiple partitions, but again the smallest cluster size is 4K even if the partition is <2TB.
3) Windows XP will recognize the >2TB MBR partition and any other partition(s). But won’t recognize any GPT partition.
DVDShrink
1) On the externals (both 3TB Seagates, a 3TB Hitachi and a 4TB Seagate), when trying to open a DVD .iso, The Parameter is Invalid error occurs. This is true no matter if the drive is MBR or GPT, doesn’t matter whether the partition is less than or greater 2TB.
2) HOWEVER, the same .iso can be opened with DVDShrink on my other drives (3TB internal in an multi-drive external case, 4 & 6TB internals), all GPT with 2TB partiions. The 4 & 6TB drives are a mix of Seagate, WD and Hitachi. The 3TB internal a WD
3) AND, if I take the 3TB internal drive (which works) and connect it to the Seagate external interface, the. iso opens.
4) SO, it seems that there’s something odd going with those particular externals I tried. I even switched the USB interface on the Seagates in case there’s some firmware difference, still the same.
5) The same error message occurs with DVDShrink on WinXP (both 3TB Seagates set to MBR). I can’t test the other drives because they’re all GPT. -
Thanks for the additional info lingyi.
So I assume not being able to create MBR partitions greater than 2TB with XP is some sort of artificial limitation, given Easeus Partition Manager can do it.
Maybe XP is just "hard wired" to expect 512 byte sectors, but for Vista and newer, can you format drives as MBR with 4k sectors, or does Microsoft force you to use GPT, even for the 64 bit versions?
From your testing it'd appear the USB bridge is causing the problem, but being able to open an ISO file on a USB drive if it was originally saved to the drive while it was connected internally, that seems a bit odd. -
This is my very simplified understanding of what's going on and I look forward to others correcting any errors.
The 2TB limit is real. What EPM does is in a way artificial because is uses the Advanced Format drives capability of internally merging 512 byte sectors into 4K ones, just as the manufacturers do. Note that officially Easeus doesn't allow the creation of >2TB partitions.
Maybe XP is just "hard wired" to expect 512 byte sectors, but for Vista and newer, can you format drives as MBR with 4k sectors, or does Microsoft force you to use GPT, even for the 64 bit versions?
From your testing it'd appear the USB bridge is causing the problem, but being able to open an ISO file on a USB drive if it was originally saved to the drive while it was connected internally, that seems a bit odd. -
That kind of makes sense....
The one thing I can't get my head round is the fact I keep reading XP doesn't support 4k sectors. The following specifically mentions USB hard drives.
(Paragraph 5)
http://en.wikipedia.org/wiki/Master_boot_record#Partition_table_entries
For disks that present a sector size other than 512 bytes, such as USB external drives, there are limitations as well. A sector size of 4,096 results in an eight-fold increase in the size of a partition that can be defined using MBR, allowing partitions up to 16 TiB (232 × 4096 bytes) in size. Versions of Windows more recent than Windows XP support the larger sector sizes as well as Mac OS X, and the Linux kernel has supported larger sector sizes since 2.6.31 or 2.6.32.
The above seems to imply Win XP doesn't support the 4k sectors reported by USB hard drives, yet we all know XP will see the full capacity of a pre-formatted USB drive. If the Windows XP reference needs qualifying..... ie it can't format a drive with 4k sectors but it'll play nice with a pre-formatted one..... that'd make sense. I've just not been able to find anything to confirm that's the case. If it's not then obviously there's something else going on.
It seems the drive manufacturers (Hitachi and Seagate, at least) have software for using drives larger than 2TB with XP. The software needs to be installed though. I assume it's a kind of "driver".
http://knowledge.seagate.com/articles/en_US/FAQ/218619en?language=en_US
A 3TB disk drive in a legacy BIOS and Window system will need a DiscWizard device driver to access the full capacity of a 3TB disk drive. Two partitions will be necessary because of the MBR limitation. The device driver mounts the capacity above 2.2TB with another MBR which looks to the system as a second virtual “physical” device.
http://hitachi-gpt-disk-manager1.software.informer.com/2.0/
The HGST GPT Disk Manager works by augmenting your Windows systems to add support for GPT (GUID Partition Table) for hard disk drives exceeding 2.2TB.
So they do it different ways, but I found it interesting as the Seagate method of of using a virtual device seems similar to the info I found in another forum (links in previous post) where the drive in a USB case appeared to contain 3 partitions when connected directly via SATA, but with the USB adaptor in between it appears to Windows as a large, single partition. I don't quite understand how that'd work. Well.... I don't understand it at all.