[OmniOS-discuss] Connect single USB disk to OmniOS ? Filesystem options?

[Svavar Örn Eysteinsson]

Thanks for the reply.

I just read on many different places on the net that single disk zpool was not
a wise choice..
for an example : 

"single disk ZFS is so pointless it's actually worse than not using ZFS".

Technically you can do deduplication and compression.

But there is no protection from corruption since there is no redundancy.  So any error can be detected, but cannot be corrected.  This sounds like an acceptable compromise, but its actually not.  The reason its not is that ZFS' metadata cannot be allowed to be corrupted.  If it is it is likely the zpool will be impossible to mount (and will probably crash the system once the corruption is found).  So a couple of bad sectors in the right place will mean that all data on the zpool will be lost.  Not some, all.  Also there's no ZFS recovery tools, so you cannot recover any data on the drives.  You cannot use the standard recovery tools that are designed for NTFS, FAT32, etc either.  They don't work correctly.

So what does all of this mean?  It means that you run the risk of everything being just fine, and then suddenly (and without warning) all of the data is irretrievably lost.

This is obviously much worse than using something like NTFS which, when faced with corruption, will simply delete the offending entries (so some data will be lost, but not necessarily everything).  You can also do some amount of recovery with things like chkdsk (no equivalent exists in the ZFS world).  You can also use some recovery tools that exist if things get really bad (no equivalent exists in the ZFS world).

So can you do what you want?  Yep.  But doing it is worse than simply using NTFS or whatever "legacy" file system you choose.  I could easily argue that if your data is that unimportant you should simply delete it.

Just wanted to double check the people opinions on this matter.



> On 12 Jul 2017, at 10:10, Peter Tribble <peter.tribble at gmail.com> wrote:
> 
> 
> 
> On Wed, Jul 12, 2017 at 10:56 AM, Svavar Örn Eysteinsson <svavar at pipar-tbwa.is <mailto:svavar at pipar-tbwa.is>> wrote:
> 
> Hello.
> 
> I need to connect a single USB disk to my HP Microserver NL54 running OmniOS.
> Going to utilize it as a backup disk for some resources on my home LAN.
> The Microserver does have many USB ports that would be fine to utilize, as I have filled the 3.5" slots in the server
> in RAIDZ modes.
> 
> The thing is, what options do I have as formating the disk? Is it only the ancient UFS and
> the FAT32 which is not going to do it's job because of file size limit ?
> 
> And correct me if I'm wrong, ZFS on a single disk is not a nice job.
> 
> Why not?
> 
> ZFS is better than UFS or FAT. It'll tell you when your data is corrupted,
> which the others won't. If you want extra protection and have enough
> space then set copies=2 (lose the space, but you get self-healing back).
> Do set LZ4 compression, there's no reason not to these days.
> 
> Just because you can't take advantage of all of the ZFS benefits doesn't
> immediately make it unsuitable, when the alternatives don't even have
> those features at all.
>  
> btw, I do have 16GB ECC memory on the HP Microserver.
> 
> As OpenIndiana distro has the NTFS fuse modules available, but there isn't any available
> for OmniOS. Any reason why?
> 
> So my options are what, UFS and FAT32 ?
> 
> ZFS. Although the one consideration for a backup drive is what you're
> going to connect it to. (Which again says ZFS, because you can then
> import the pool on another system pretty easily.)
>  
> -- 
> -Peter Tribble
> http://www.petertribble.co.uk/ <http://www.petertribble.co.uk/> - http://ptribble.blogspot.com/ <http://ptribble.blogspot.com/>
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