Recommended zpool creation options?

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Recommended zpool creation options?

Post by mkush » Wed Sep 26, 2012 9:52 pm

I'm having a hard time finding a good source for what options would be good to use when creating a zpool to make it the most Mac-like or Mac-friendly. I quickly learned that the volumes are case sensitive by default which is not "normal" for Macs. So I am using -O casesensitivity=insensitive. The capital O got me at first, lowercase doesn't work. I also used -o ashift=12 since I'm using advanced format drives.

But, I have seen reference to other options being used, for example utf8only and normalization. What of those and others I should consider?
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Re: Recommended zpool creation options?

Post by grahamperrin » Thu Sep 27, 2012 12:50 am

normalisation

From the man page for zfs:

The default value of the normalisation property on Mac OS X is formD. This property cannot be changed after the file system is created.


utf8only

If (the normalisation) property is set to a legal value other than none, and the utf8only property was left unspecified, the utf8only property is automatically set to on.


copies

This may be set to 2 or 3, but for the vast majority of use cases I should recommend the default (1). More on this in a future topic.

compression

If you require compression, the most common recommendation is
compression=on

Levels as high (as CPU-hungry) as gzip-9 are possible but not advisable for general use. Discussion …
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Re: Recommended zpool creation options?

Post by si-ghan-bi » Thu Sep 27, 2012 3:56 am

Case sensitivity: I suggest to use it, as you wrote: -O casesensitivity=insensitive

I also suggest mentioning it on the quickstart guide: people not knowing about the sensitivity issues are probably the ones that really need INsensitivity, better give them immediately the correct command line in the guide. If they format big drives as INsensitive and later find out the problem, they may not have any way to move the data somewhere else and reformat.
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Re: Recommended zpool creation options?

Post by mkush » Thu Sep 27, 2012 8:14 am

si-ghan-bi wrote:Case sensitivity: I suggest to use it, as you wrote: -O casesensitivity=insensitive

I also suggest mentioning it on the quickstart guide: people not knowing about the sensitivity issues are probably the ones that really need INsensitivity, better give them immediately the correct command line in the guide. If they format big drives as INsensitive and later find out the problem, they may not have any way to move the data somewhere else and reformat.

I second the idea. This is a product for Macs, so it is logical to mention the most common (least problematic) usage on Macs.

So, regarding the previous post, do you suggest also setting the normalization and utf8only values to formD and on, respectively? (Although it sounds like the utf8only value could be left unspecified, but always better to be specific.)
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Re: Recommended zpool creation options?

Post by shuman » Thu Sep 27, 2012 9:57 am

Third time's the charm for me. . . hopefully. How does this look?

zpool create -O casesensitivity=insensitive -O normalization=formD zdata mirror /dev/disk1 /dev/disk2

I wonder if the casesensitivity flag is redundant when using formD? Either way this worked for me. Did I miss anything that might be necessary for standard Mac use?

It appears that any additional filesystems created in this pool will inherit the same properties.
- Mac Mini (Late 2012), 10.8.5, 16GB memory, pool - 2 Mirrored 3TB USB 3.0 External Drives
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Re: Recommended zpool creation options?

Post by si-ghan-bi » Thu Sep 27, 2012 10:05 am

Those are already the standard values under OS X, as grahamperrin already wrote. Have you tried creating a pool and then checking what it comes out?
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Re: Recommended zpool creation options?

Post by shuman » Thu Sep 27, 2012 10:10 am

Running the following command yielded a case sensitive FS.

zpool create zdata mirror /dev/disk1 /dev/disk2

That's why I had to destroy it and start over.

Here is my previous post with property value of sensitive.

http://zevo.getgreenbytes.com/forum/viewtopic.php?f=4&t=85&p=405#p405

NAME PROPERTY VALUE SOURCE
zdata casesensitivity sensitive -
- Mac Mini (Late 2012), 10.8.5, 16GB memory, pool - 2 Mirrored 3TB USB 3.0 External Drives
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Re: Recommended zpool creation options?

Post by mkush » Thu Sep 27, 2012 12:58 pm

Yeah, definitely case *sensitive* unless you use the option. So the question remains: should we be using the normalization and utf8only or not? Maybe what is lacking is a good explanation of what those really are. Again, my goal is to make the volume the most Mac-like possible unless it takes away some ZFS "goodness".
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Re: Recommended zpool creation options?

Post by si-ghan-bi » Thu Sep 27, 2012 2:06 pm

I meant the other two options are already standard in OS X, of course not the case sensitivity, that should be set manually.

I don't know which settings for the utf8only and normalization are best for mac, but given the description and given that the defaults for them are specific for mac (grahamperris explained it), maybe they have been already tuned.
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NFD: normalization=formD (normalisation form D)

Post by grahamperrin » Thu Sep 27, 2012 10:59 pm

NFD: normalization=formD (normalisation form D)

mush wrote:… normalization and utf8only … Maybe what is lacking is a good explanation of what those really are. …


When I puzzled over this a few months ago, I probably used a May 2012 post by xoa in Ars Technica to help me decide.

For more depth, maybe read alongside each other the Wikipedia pages for HFS Plus and Unicode equivalence.

Also (thanks to someone in a private beta):

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