NAS setup recommendations

Matthias Play matthias_play at
Mon Jan 26 14:35:46 PST 2015

Thanks for your suggestions.

In the end I managed to get RAID1 (using vinum) running for /boot and 
data parts. Also all data is encrypted utilizing dm except for the boot 

I found an interesting link (do not have it at hand on this machine) 
describing how to setup slice partitions enabling vinum RAID setup using 
UFS that is required for the boot part.

The idea is to overlay a UFS partition with the vinum part such that the 
vinum offset defines the start of the UFS partition enabling normal UFS 
access during boot.

For testing I have taken the example scripts in the rconfig dir and 
wrote scripts for the following setups:

1. 'a' for /boot, 'd' for / in vinum RAID1 config formatted with hammer
2. like 1. with encrypted / with dm
3. like 1. with /boot in vinum RAID1 config
4. like 2. with /boot in vinum RAID1 config

In the end I also tested a data recovery scenario when using the Marvell 
RAID chip on the mobo. Recovery would seem to work well in case there is 
a HW failure since the first 16MByte are only used by the chip to store 
its RAID configuration data. So, using dd with skip=16 bs=1M discards 
the RAID header.

That is why I will use the HW RAID for the data part and also decided to 
use an extra SSD not doing a RAID for the OS part, but instead using 
hammer mirroring for OS configuration files that would be needed in case 
of SSD failure.


Am 22.01.2015 um 08:05 schrieb Mehmet Erol Sanliturk:
> On Wed, Jan 21, 2015 at 6:45 PM, Predrag Punosevac
> <punosevac72 at <mailto:punosevac72 at>> wrote:
>     Matthias Play wrote:
>      > Hi Mehmet,
>      >
>      > thanks for your quick reply and suggestions!
>      >
>      > I would prefer to also always have a 1:1 copy of the OS part,
>     because I
>      > also want to avoid exactly what you described i.e., do an extra
>     install
>      > and configuration.
>      >
>      > It would maybe be sufficient to only do a cpdup from time to time to
>      > keep the OS copy up to date. I think this could be a good compromise.
>      >
>      > Regards
>      > Matthias
>     Well the "correct" way to build the NAS would be to install DF on two
>     embedded SSDs and have data on regular HDDs as Mehmet suggested. One
>     would want to have RAID 1 on those two embedded SSDs or two have HAMMER
>     mirror stream. Unfortunately AFAIK current installer supports neither.
>     On the top of it HAMMER slave drive is read only so it would take human
>     intervention to have a "graceful" failover in the case one HDD dies.
>     My understanding that HAMMER2 will not have that problem as the slave
>     will be writable.
>     Yes DF could be molded into wonderful NAS product with little bit of
>     corporate backing :)
>     Cheers,
>     Predrag
> The installer is not very much a problem :
> First install operating system on a disk or some more ( dd may be used )
> as kept spare .
> After installation of the operating system , attach ( other ) disks for
> data storage and make a file system on them .
> Advantage of separation of operating system from data disks is defined
> in my first message :
> In that way any operating system change will not affect data disks .
> Installation of a new version of operating system on existing data disks
> requires save and restore of existing data ( or install on another
> computer and copy existing data ) . When size of data is large , such an
> operation may require days .
> Thank you very much .
> Mehmet Erol Sanliturk

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