help creating new gmirror > 2TB

[JD]

I thought that hdparm could work with the firmware to set the sector size.
Not sure on this because hdparm has gone through a lot of modifications
over the years.

On 08/30/2017 06:35 PM, William Dudley wrote:
> I've never heard of AFD, and is having 4K sectors something I have control
> of?  Or is tthat something the manufacturer controls?
>
> My drives are: 2 of Seagate 4TB IronWolf NAS SATA 6Gb/s NCQ 64MB Cache
> 3.5-Inch Internal Hard Drive (ST4000VN008)
>
> Which doesn't have the magic word "AFD" anywhere in the description.
>
> Also, I happen to like the idea of "fixing" the gmirror code to put it's
> metadata in the penultimate sector if it discovers GPT
> in the last sector, but I suppose I shouldn't get my hopes up.
>
> Bill Dudley
>
> On Wed, Aug 30, 2017 at 5:57 PM, Frank Leonhardt <frank2 at fjl.co.uk> wrote:
>
> "I'm sure you'll be okay with MBR assuming it's an AFD (4K sector drive)."
>
> On 29/08/2017 21:12, William Dudley wrote:
>>> Hi,
>>>
>>> I want to create a simple mirror > 2TB on a FreeBSD 10.3 system.
>>>
>>> I have 2 identical 4TB disks.
>>>
>>> The examples in freebsd handbook "geom-mirror" pages show creation of a
>>> 2TB
>>> mirror using
>>> MBR partitioning, and that has an upper limit of 2TB.
>>>
>> I still get a bit worried about this, but I'm 99.9% sure you'll be okay
>> with MBR assuming it's an AFD (4K sector drive). The bodge/workaround
>> works. If it's SAS instead of SATA, all bets are off.
>>
>> Although I use ZFS a lot, I still prefer geom mirror for twin-disk
>> systems. I feel a lot more comfortable booting from it in the event of a
>> failure. ZFS has its good points, but so does UFS.
>>
>> Trying to get geom mirror to work with GPT as it stands just leads to
>> pain. I've taken a look at the code with a view to fixing this is no one
>> else does, but UFS is so un-cool in most circles and I don't fancy doing it
>> alone in case I zap someone's data. it doesn't look that tricky to move the
>> metadata somewhere else, and by checking for a GPT you can select between
>> the old/new block. It's unexpected interactions I'm worried about.
>>
>> I think we're safe with MBR until we pass 16Tb.
>>
>> Regards, Frank.
>>
>>
>>
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