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DiracDeBroglie

Cannot create an Extended Partition (Volume) on an external USB 3.0 en

18 posts in this topic

Hi,

I got a 2TB drive (4K physical sector) in an external USB 3.0 (2.0) enclosure. With my old laptop (Windows XP) I can without any problem partition the drive into several primary partitions and several logical partitions within one extended partition. Note: the enclosure works in USB 2.0 mode on the old laptop.

However, with my new laptop (Windows 7) I cannot at all create any (basic) extended partition. Disk Management in Win7 only gives me the format options New Simple Volume, New Spanned Volume and New Striped Volume. New Spanned Volume and New Striped Volume do not work at all on my drive. New Simple Volume does work but creates only and automatically (basic) primary partitions. There is no way I can create an extended partition with in there logical volumes (or partitions). Under Win7 the enclosure works in USB 3.0 mode.

Why is it that I cannot create extended volumes (partitions) in Win7??

johan

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...with my new laptop (Windows 7) I cannot at all create any (basic) extended partition...

Hi!

You may create no more than three primary partions (if you create a fourth one the whole HDD would be considered as dynamic as soon as you include another drive).

After the third primary partition you may create so many logical units as you wish. After including a first logical unit the whole remaining HDD becomes automatically an extended partition. You may see it as a light-blue coloured disk space at the disk manager.

HTH

Edited by cannie
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On WinXP I can create a primary partition and right after a second partition which is an extended one. Under WinXP I have an absolute grip on the type of partition, which is not the case in Win7.

In Win7 I can only create primary partitions, but no extended partitions. In Win7 DM (disk management) I rightclick the unallocated drive; then the only format possibility that pops up is New Simple Volume, which seems to be a basic primary volume. I think there must be a problem with Win7 DM, as DM in WinXP works just fine.

So, what could be the problem in the Win7 DM?

johan

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... the only format possibility that pops up is New Simple Volume....

You may also create logical units. But for best results you may use "Partition Wizard" . Download the freeware Live CD .iso file ("Free Dowload Bootable CD Now!), deploy it into a folder and execute Partition Wizard.exe

HTH

Edited by cannie
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The problem I have is DM in Win7. Is it so that in Win7 DM it is not possible to create an ordinary (basic) Extended partition with several logical partitions on an external USB drive?? In WinXP all is ok, I can create an Extented partition with several logical partitions. So, why can it not be done in my Win7 DM? Does anyone really understand the problem I have?

johan

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Is it so that in Win7 DM it is not possible to create an ordinary (basic) Extended partition with several logical partitions on an external USB drive?...

AFAIK it is not possible by using the old XP procedure, not even in your internal HDD. But you may directly create as many logical units as you wish, no need of a previous Extended partition.

Edited by cannie
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Just found a link which worries me:

http://97.95.43.80:10080/632/

So, it looks like DM in Win7 always chooses a primary partition, and only dedides to create an extended partition when creating a 4th partition. Can anyone confirm that?

Furhtermore, DM in Win7 is a bit confusing if you ask me. DM offers me to format the drive in a New Simple Volume, New Spanned Volume or New Striped Volume. Only New Simple Volume works and so DM should than create dynamic disc, but DM doesn't do that. Instead it creates a basic volume (primary), which you should be able to convert to a dynamic disk, but that also does not work either. Strange!

johan

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It seems the only way is running diskpart under cmd.exe with the command 'create partition extended'. Thus not using DM.

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So, it looks like DM in Win7 always chooses a primary partition, and only dedides to create an extended partition when creating a 4th partition. Can anyone confirm that?

Yes. And the size you set for 4th "volume" is the size Win7 Dm sets as the size of the 1st logical drive inside an extended partition that takes the whole remaining space of the drive. Which makes sense as you theoretically won't be able to create a 5th partition.

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I prefer to use something with a graphical user-interface, so DM. I am still doubting DM cannot create an extended partition before having 3 primary partitions first. Ponch, could you confirm what I have experienced with DM under Win7?? Is it really true that Win7 DM can only create an extended partition after having 3 primary partitions first?? (it is so bloody illogical of Win7 DM)

In the Help Topics of DM, I coundn't find anything about the user NOT having the flexibility to choose at the beginning of the formatting process between primary or extended basic partititions. It looks like Microsoft doesn't communicate very clear about the limitations of DM in Win7, something that should definitely be done as under WinXP DM offers right away the choice between a primary or an extended partition. In WinXP I can format the entire drive right way into an extended partition, no way in Win7.

I've been trying out things and there is a very simple way to get an extended partition using DM in Win7. For instance, if one wants an extended partition starting from a particular position (track), just fill up the disk space before that position with 3 primary paritions (of whatever size each). The 4th partition is then automatically an extended one. If one only needs only one primary partition, the 2nd and 3rd primary partition can be deleted, followed by an extension or expansion of the 1st primary covering all space until the beginning of the extended partition. That procedure gives you 1 primary and 1 extended partition; I know, it is cumbersome and Diskpart does it more elegantly but if one wants to use the Graphical User-interface, that is the way to do it I think.

I noticed that shrinking/deleting a logical volume in Win7 DM is not really a problem, but shrinking the extended partition enclosure surrounding the logical partitions seems more difficult, as opposed to extending/expanding an extended partition, which works well.

So, if one want the entire drive formatted as an extended partition, then create 3 primary partitions totalling a disk size smaller than the drive size (the 4th part remains unallocated), delete the first partition (becomes unallocated), partition the 4th part (automatic primary), and then partition the first unallocated part. The first partition is then automatically an extended partition. Then delete all primary partitions, and expand the extended partition to the end. The entire drive is then an extended drive.

Apart from the primary-extended partition issue, there is also the issue of formatting the drive into a basic volume or a simple volume. Right clicking the unallocated area of the drive in Win7 DM makes the DM to offer you the option to format the drive in New Simple Volume. New Simple Volume is a dynamic volume; however, if I continue to format as New Simple Volume, then primary and extended volumes appear, which are basic volumes, but there is definitely no dynamic volume on my drive. So DM seems to take the decision to create a basic volume instead of a dynamic volume without any notification nor any warning, although I asked in principle for a dynamic volume (New Simple Volume). Completely nuts!!

johan

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Just discovered something. The work-around I explained in my previous post for creating extended partions works only for MBR drives, not for GPT drives. Under GPT, Win7 DM just keeps on creating primary partitions; just did the test with more then 10 partitions, they were all primary. So, I assume under GPT the only way to create an extended partition is by using diskpart. I have to say Microsoft really messed it up with their Win7 DM.

johan

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Hi, Cluberti,

Thanks for the link. I checked it out, definitely useful. The link didn't mention with so many words, though, that extended partitions don't exist under GPT. Furhermore, www.uefi.org didn't really provide me with any useful or conclusive info either about the exclusion of extended partions on GPT drives.

After some Googling on the net, I discovered just a few forums and blogs were it is simply mentioned in the discussion that extended partitions don't exist on GPT drives. I find it very difficult to get or to lay my hands on any official document stating very explicitly that extended partitions don't exist in the GPT world.

For the past 20, 30 years PC drives have been partitioned in primary and extended partitions. Any ICT person, any advanced user, anybody using a computer the past 20 years knows the notion "extended partitions". So, also for me the notion of extended partition is part of my genetics, and it didn't even occur to me that under Win7 there would be anything that could lack the notion of extended partition.

I would find it trivial and obvious that in any (official) communication from MS, Intel or www.uefi.org about GPT they would clearly mention that extended partitions (or volume) don't exist at all.

Anyhow, I am probably not going to use GPT as I've now realised GPT is not compatible with my WinXP laptop.

johan

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Hi Jaclaz, how're doing, the very best for the new year, seasons greetings,

Just had a look at your links. Looks like it could be quite a hassle to get a WinXP computer communicating with a GPT drive. The 2TB (external USB enclosure) of mine is intended as backup drive in the first place, although I'll keep the first 100GB or so as primary for future booting. I think 4 (primary) partitions will do in my case. If I need more than 4, then I'll have to decide between MBR with an extended partition or GPT. I don't feel for putting to much hassle and effort in getting the WinXP laptop and the 2TB drive to communicate; so I got a preference for MBR partitioning. If for some reason I have to partition the drive into GPT, then I can still backup the WinXP laptop over the home network and via the Win7 laptop.

The main decision still to take from my side is the partition layout for the drive. That'll depend very much on the data that I will backup next coming years. One issue still left which I see is important in deciding how to work out the partition layout is related with another post of mine:

johan

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The main decision still to take from my side is the partition layout for the drive.

Decisions, decisions, always decisions....

Everyone has his/her own preferences.

The only thing that is important as I see it is to take a decision (anyone) in an informed way.

What I normally do is to (expecially for a DATA drive):

make only one small primary partition

make as many logical volumes inside the extended partition spanning over the rest as I see fit (the more, the better)

Having DATA catalogued in different partitions allows for:

  • easier selective backup/imaging
  • easieer/faster partition defrag/chkdsk
  • greater "security" against some types of wiping malware

You don't really have to have a drive letter for each volume, as you can use mountpoints allright.

Of course what I personally do is completely unlike what most other peeps do (just make one huge, big partition and let it be) which I personaly find the most unconvenient and worse than that the most unsafe setting.

A computer is nothing but a metaphor of a normall office/archive.

Imagine that you have a nice file cabinet with (say) 6 drawers.

Now what are you going to do, label drawers with (again say) "Customers", "Suppliers", "Invoices", "Projects", "Legal matters" , "Other" and put in each drawer the appropriate content or do you remove the drawrs and just stack everything inside the resulting "empty" cabinet? :unsure:

JFYI:

jaclaz

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I'm also in the opinion to partition the drive in several partitions. I think you have a strong point (in your link) favoring logical drives in a extented partition. Extended partitions have their own EPBRs inside the extended partition and not on sector 1, where any accidents in sec1 or track0 could cause lot of hassle. Logical drives should therefore be easier to repair in case of havoc. Actually, I recently learned that GPT partitions have similar protection as the 34 GPT primary sectors have a 34 secundary sector backup at the other end of the drive.

Things might be different with virusses. Only "dumb" virusses may limit themselves to destroyng sec1, track0 thereby making it relatively easy to reconstruct logical MBR partitions and GPT partitions. However, I never heared about "dumb" virusses---they are all smart; so it likely that bad intentions on the drive will just wipe out ALL partition info where ever on the drive.

By the way, aren't there any tools available that could backup (onto another medium) the MBR or GPT of a drive and restore it in case of trouble?

Johan

Edited by DiracDeBroglie
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