A n00b here wanting some general advice

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A n00b here wanting some general advice

Postby ylluminarious » Tue Jun 20, 2017 11:21 pm

Fyi, this was migrated from #openzfs-osx:

So, I've never really used ZFS before and only have a fairly basic
understanding of it. I'm interested in it because of some experiences
that I've had which highlight the incompetence of HFS+ (and upon
reading about the up and coming APFS, I'm not extremely excited about
it either since it seems to fall short of ZFS on a number of points),
so I'm interested in migrating some volumes I have to ZFS. I've
installed openzfs, but I'm not 100% sure on where to go from here. I
assume that the next steps to take are to back up the volumes I'm
interested in, unmount them, add each one to a respective zpool (i
just want them to be individual volumes formatted to ZFS, not to be
aggregated into a single zpool [at least that's what I think for the
time being]), and then migrate the data over to the new ZFS volumes /
zpools. Also, I'm interested in converting & migrating my root volume
to ZFS... although I assume that this means I need to follow the guide
to make ZFS bootable on my system, which I take it is a somewhat risky
procedure. Oh, also, what's the deal with ACLs in openzfs? According
to the wiki, they don't work yet, but the ticket that it links to is
closed:
https://openzfsonosx.org/wiki/FAQ#Q.29_ ... ka_ACLs.3F. Anyway,
am I headed in the right direction with my thoughts here or not? Feel
free to point out any flaws on my part or suggestions. TIA
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Re: A n00b here wanting some general advice

Postby lundman » Wed Jun 21, 2017 4:48 pm

We touched upon it in irc a little bit, but here goes...

A single HDD pool will work fine, but you will get no redundancy from it at all. So if the disk dies, you lose all your data. One thing ZFS is great at, is putting all the HDDs into a pool, with redundancy, so you can lose a HDD, replace it, and not lose any data. If you have one pool, for all your HFS volumes, you can still set the same hard disk space limits you have now, if you really wanted to. But if you don't, one of your volumes can grow larger than just the one disk, should you find that it needs to. Having redundant data is always desirable, but it does make it trickier to get the data on there, if you do not have lots of spare space.


However, even using ZFS on single disk pools does still give you some great benefits over HFS. Your data is checksummed against bitrot, and you can protect the data further using snapshots - in case of operator mistakes. ZFS send/recv makes for excellent off-site backups and all that extra goodness.

After that, backup data on a volume, erase it and create a pool on it.. some care is needed for the options when creating a pool (check the wiki, you want case-insensitive and formD etc.). Then restore the data back.


As for booting, it is a bit more advanced. It isn't quite ready for mass-use, but can be fun to play with. HFS on a ZVOL is a reasonable compromise, with full compatibility. But I would hold off on this for a bit.
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Re: A n00b here wanting some general advice

Postby ylluminarious » Thu Jun 22, 2017 10:58 am

lundman wrote:We touched upon it in irc a little bit, but here goes...

A single HDD pool will work fine, but you will get no redundancy from it at all. So if the disk dies, you lose all your data. One thing ZFS is great at, is putting all the HDDs into a pool, with redundancy, so you can lose a HDD, replace it, and not lose any data. If you have one pool, for all your HFS volumes, you can still set the same hard disk space limits you have now, if you really wanted to. But if you don't, one of your volumes can grow larger than just the one disk, should you find that it needs to. Having redundant data is always desirable, but it does make it trickier to get the data on there, if you do not have lots of spare space.


However, even using ZFS on single disk pools does still give you some great benefits over HFS. Your data is checksummed against bitrot, and you can protect the data further using snapshots - in case of operator mistakes. ZFS send/recv makes for excellent off-site backups and all that extra goodness.

After that, backup data on a volume, erase it and create a pool on it.. some care is needed for the options when creating a pool (check the wiki, you want case-insensitive and formD etc.). Then restore the data back.


As for booting, it is a bit more advanced. It isn't quite ready for mass-use, but can be fun to play with. HFS on a ZVOL is a reasonable compromise, with full compatibility. But I would hold off on this for a bit.


Thanks for reiterating these points and going into more depth with them. Definitely good stuff to keep in mind, and I think I'm going to actually go ahead and use a single pool for both volumes when I take the time to play around with this.

One point you didn't mention that I'm still curious about -- what's the situation with ACLs in openzfs?

Thanks again.
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Re: A n00b here wanting some general advice

Postby lundman » Fri Jun 23, 2017 4:03 pm

It's unusual to actually use ACLs, but ZFS had full ACL capability, what IS missing however is the UI integration of them. So you can not use, say, Finder, to change ACLs. You have to pop open terminal, and use chmod like all the elite hackers.
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Re: A n00b here wanting some general advice

Postby ylluminarious » Fri Jun 23, 2017 11:03 pm

lundman wrote:It's unusual to actually use ACLs, but ZFS had full ACL capability, what IS missing however is the UI integration of them. So you can not use, say, Finder, to change ACLs. You have to pop open terminal, and use chmod like all the elite hackers.


Alright, great, thanks for the info. No problems here with using the terminal like a 1337 haxx0r ;D
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