Is it possible to create a software RAID 1 with different sector sizes?

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I bought a hard drive of a different model to my main drive and tried to mirrored them, but the following error message came up in Windows 7 Virtual Disk Manager:

All disks holding extends for a given volume must have the same sector size, and the sector size must be valid.

My disks have the following stats:

Main drive: SAMSUNG HD103SI, physical sector size 512b.
Mirror drive: WDC WD10EARX, physical sector size 4096b.

Running chkdsk they both report 4096 bytes in each allocation unit, which I assume is another way to say "virtual sector size".

Do the physical sector sizes have to match? Can I somehow reformat a drive to match the other? It'd be nice if I could use different drives, then I could step-wise upgrade in the future.

I was thinking that I could clone my main drive to my mirror drive and then use the main drive as a mirror instead. Would that work, or it would just be a huge waste of time?

EDIT: I noticed that I can create a mirrored volume on both drives from 2 unallocated drives. but when I create a volume first, right click it and then try the option "add mirror" it always gives the "sector size error" message to me. is this a bug? Why does add mirror" not work?

Anyway, assuming I will have to reinstall windows 7 on them, I am going to follow this guide here and well see how it goes: http://my.opera.com/Devocalypse/blog/2011/03/02/install-windows-7-on-a-dynamic-disk-pro-and-ultimate-only

EDIT: It works. Managed to install Windows on the "mirrored volume" by following the guide, however I still want to copy/clone my current "main volume" to the dynamic disk.

EDIT: Bought another identical disk this time and now the "Add Mirror" button works. I clone the data onto the new disk then boot from there then I press "Add mirror" and it works. Now I am trying to figure out why the other mirrored drive won't boot.

ColacX

Posted 2011-12-13T02:01:52.930

Reputation: 921

1The "allocation unit" is the cluster size for NTFS. Functionally, I think it's the same as what you mean by "virtual sector size"... it's what the filesystem is using as the minimum allocation size. You won't be able to reformat one to match the other, but cloning should work if your disks are well supported. I'm surprised at the limitation... no idea how to fix it. – mgjk – 2011-12-13T13:35:01.257

Thanks for your comment. Sad :( i thought so. Oh well hopefully someone else benefit from this post. – ColacX – 2011-12-13T21:03:15.510

so i decided to do the next best thing. i cloned the drive (with EASEUS partion manager free home edition, copy dynamic disc volume to basic-drive) and soon ill buy a new drive and mirror it.i got the clone to boot and run but its running oddly slow/spiky and for some reason chkdsk cant get to stage 1 it just freezes on stage 0, anyone know why??? im going to try rebooting a few times. – ColacX – 2011-12-16T20:16:03.080

oh sweet i restarted the computer once and windows 7 said driver installed for new drive and you must reboot, i did and chkdsk works perfectly now. i guess it couldnt figure out which driver to use on the first boot. – ColacX – 2011-12-16T20:32:13.210

crap i bought a seagate ST2000DL003 which should have the same sector size, they both should be advanced format too. and i still get the same error. im thinking that i need to reinstall windows but i dont really want to (mostly for my curiosity). not sure that the drive brands / models should not work with each other anyone that can share some light on this? – ColacX – 2011-12-20T18:20:47.017

So your clone was successful but now when you try to mirror to your new Seagate it is telling you that your WD has 512 byte physical sectors?(!!) – mgjk – 2011-12-20T19:12:10.273

no they still says 4096 like always. i dont know why it just doesnt work. same error message. – ColacX – 2011-12-22T22:46:18.550

@ColacX Did you clone a 512b HDD onto a 4k Advanced Format drive? I would only do this with the very latest clone tools with specific support for 4k. If the tool doesn't have specific support, your partition may not be aligned on 4k boundaries, and therefore read/write will be miserable. – Dom – 2013-08-22T06:46:53.317

1Also, it's unlikely mirroring would work well between a 512b and 4k drive. The 4k drive should be able to be converted to a 512b legacy mode, but it's still cost effective and it's best practice for a number of reasons just to buy another 4k drive - they're not expensive. – Dom – 2013-08-22T06:48:03.650

Answers

2

Yes, it is possible to run RAID-1 on harddrives with different physical sector sizes.

Having said that, it might not be a good idea. If your software RAID-1 implementation writes in 512 bytes chunks then it will be inefficient and slow. This is probably not a problem since most filesystems use chunks of 4k and most stripe sizes on RAID are 64Kb or larger.

However in rare cases you could get really bad performance. Especially if you did not align the filesystem on a 4k boundary.

Hennes

Posted 2011-12-13T02:01:52.930

Reputation: 60 739

There isn't really a stripe size with RAID 1. Reads and writes can both be executed just fine without extending the operation to a whole stripe. Implementations that artificially blow up IO operations to whole stripes would just kill their own performance -- so I figure there won't be many. The only place where I would imagine finding something like a stripe number in a RAID 1 system is in a dirty block/stripe table. There it would make sense to use some number > 512 to reduce the required table size/improve performance. – Paul Groke – 2014-01-21T19:04:19.800

Asked: 2011-12-13T02:01:52.930

Viewed: 9 038 times

Active: 2014-09-27T05:58:19.397