HAST + ZFS + NFS + CARP

[Julien Cigar]

On Mon, Jul 04, 2016 at 10:55:40AM -0700, Jordan Hubbard wrote:
> 
> > On Jul 3, 2016, at 11:05 PM, Ben RUBSON <ben.rubson at gmail.com> wrote:
> > 
> > Of course Jordan, in this topic, we (well at least me :) make the following assumption :
> > one iSCSI target/disk = one real physical disk (a SAS disk, a SSD disk...), from a server having its own JBOD, no RAID adapter or whatever, just what ZFS likes !
> 
> I certainly wouldn’t make that assumption.  Once you allow iSCSI to be the back-end in any solution, end-users will avail themselves of the flexibility to also export arbitrary or synthetic devices (like zvols / RAID devices) as “disks”.  You can’t stop them from doing so, so you might as well incorporate that scenario into your design.  Even if you could somehow enforce the 1:1 mapping of LUN to disk, iSCSI itself is still going to impose a serialization / performance / reporting (iSCSI LUNs don’t report SMART status) penalty that removes a lot of the advantages of having direct physical access to the media, so one might also ask what you’re gaining by imposing those restrictions.

I think the discussion evolved a bit since I started this thread, the
original purpose was to build a low-cost redundant storage for a small
infrastructure, no more no less.

The context is the following: I work in a small company, partially
financed by public funds, we started small, evolved a bit to a point
that some redundancy is required for $services. 
Unfortunately I'm alone to take care of the infrastructure (and it's 
only 50% of my time) and we don't have that much money :( 

That's why I was just thinking of two machines with a simple HBA card, 
2x4To, a zpool mirror on those 4 disks (2 local, 2 iSCSI exported), a 
NFS share on top, and an easy failover procedure..

I understand that iSCSI hides some details, but as far as I know it's
the "lowest" level that you can provide to ZFS when the disks are not
local, no ?

Anyway, thanks for your feedback, it's greatly appreciated! :)

Julien

> 
> - Jordan
> 
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-- 
Julien Cigar
Belgian Biodiversity Platform (http://www.biodiversity.be)
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