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mybook 3 TB drive - can I change sector size?

P

pesos

Junior Member
I bought a mybook 3tb usb3 drive with the intention of using it to store Hyper-V VHD virtual disk files.

Hyper-V is reporting that it cannot use drives with 4k sector sizes (way to go, microsoft). I have heard that the built-in WSB (same engine used for win7 backups) also has this limitation.

Is there any way to get 512b emulation on the MyBook drives, or do I need to return this drive and go with a different solution?

Thanks!
Wes
 
What version of hyper-V do you have?

Hyper-V 2008 R2 is supposed to have full 4k drive support (including providing virtual 512 byte sectors for VMs which don't support 4k natively).
 
I was surprised to see it as well (2008 R2), but that is the error I get only on this drive:

"the sector size of the physical disk on which the virtual disk resides is not supported"
 
Did you repartition/reformat the drive after you bought it?

This drive comes from the factory with an MBR partition table (which isn't officially supported on drives > 2 TB). However, seagate partition these drives in MBR for XP compatability (XP doesn't officially support drives > 2TB. However, XP *does* support native 4k sector drives and by using this combination of MBR partitioning and 4k sectors, it is possible to bypass XP's 2 TB limit).

However, this unsupported format does confuse some software - and I suspect hyper-V is likely to be just such a package.

What you should try is to wipe the drive, and then repartition it, making sure to use a 'GPT' partition table when initializing the drive.
 
It's the USB 3.0 version of the drive. I plugged it in and reinitialized it as GPT. I can create a 3 TB (2.7gb partition) no problem and copy files to it etc. It's only Hyper-V that freaks out. I also tried repartitioning it with MBR and created a 2 TB partition - same error. I think it is actually the physical sector size judging from the error message?
 
I guess then that the problem is that hyper-V doesn't like 4k sector disks - and I've been misled about its compatibility.

Unfortunately, I don't have a disk to test it on.
 
I'll check with western digital tier 2 on Monday in case they have a trick to turn on 512b emulation, but other than that I suppose I'll have to return the drive. Bummer!
 
Mark R said:
However, XP *does* support native 4k sector drives and by using this combination of MBR partitioning and 4k sectors, it is possible to bypass XP's 2 TB limit).
Click to expand...
Surely you jest. 4KB sectors pre-date XP by quite some time. And if WHS/Server 2003 don't support them, then surely XP doesn't either.
 
VirtualLarry said:
Surely you jest. 4KB sectors pre-date XP by quite some time. And if WHS/Server 2003 don't support them, then surely XP doesn't either.
Click to expand...

Just because they're not on the official compatability list doesn't mean they don't work (with limitations - they aren't bootable or usable as a system drive, but once the OS is running, they work fine). XP is quite happy with weird sector sizes.

To illustrate this, just look at AMD's chipset RAID. When you create a RAID 0 on an AMD mobo, the RAID drive appears to have sectors which are the size of a stripe. So, RAID together 4 drives (with 512 b sectors), and the RAID BIOS will tell the OS that is has 2k sectors. (The reason it was done this way is due to XP's limitation of 4 billion sectors on a drive - by having the RAID driver boost the sector size, you could go past the 2 TB limit).

Strange compatability issues only crop up with special server software that uses certain optimizations - e.g. SQL server (which uses its own file systems and drive access strategies), or special storage drivers (like the special non-RAID redundant storage on WHS, or VM hypervisors).
 
Mark R said:
Just because they're not on the official compatability list doesn't mean they don't work (with limitations - they aren't bootable or usable as a system drive, but once the OS is running, they work fine). XP is quite happy with weird sector sizes.

To illustrate this, just look at AMD's chipset RAID. When you create a RAID 0 on an AMD mobo, the RAID drive appears to have sectors which are the size of a stripe. So, RAID together 4 drives (with 512 b sectors), and the RAID BIOS will tell the OS that is has 2k sectors. (The reason it was done this way is due to XP's limitation of 4 billion sectors on a drive - by having the RAID driver boost the sector size, you could go past the 2 TB limit).

Strange compatability issues only crop up with special server software that uses certain optimizations - e.g. SQL server (which uses its own file systems and drive access strategies), or special storage drivers (like the special non-RAID redundant storage on WHS, or VM hypervisors).
Click to expand...

I'm pretty sure that even though it works it's not optimal because XP will still submit I/O in 512b chunks. And it's possible the 2K sector thing works because CDs have 2K sectors, so XP had to support them on certain devices.
 
Nothinman said:
I'm pretty sure that even though it works it's not optimal because XP will still submit I/O in 512b chunks. And it's possible the 2K sector thing works because CDs have 2K sectors, so XP had to support them on certain devices.
Click to expand...

Possibly. But I think it's more likely that XP is sector-size agnostic, and simply issues I/O in sector sized pieces.

Again, looking at the AMD fakeRAID - you can easily have 1k sectors (indeed, this is the more common use - 2 drives in RAID 0), and these are not a standard size for any medium.

Similarly, ATA (and SCSI) do not support partial-sector I/O, so the minimum I/O size that an OS can issue must be the size of a single sector.
 
Emulex said:
so you are really trying to run VHD's off external drive?
Click to expand...

Indeed. First of all, this is simply for one VM and it's running DPM, so performance is not critical. Second of all, USB3 performance is actually very respectable and on par with sata - more than enough for this application. The size is key here, not performance.

It's 2011 Microsoft, get with it and get 4k support patched into Hyper-V asap...
 
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