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Date:      Thu, 04 Dec 2014 14:47:40 -0800
From:      Xin Li <delphij@delphij.net>
To:        Steven Hartland <killing@multiplay.co.uk>, freebsd-fs@freebsd.org
Subject:   Re: ASHIFT=13 by default.
Message-ID:  <5480E48C.6040801@delphij.net>
In-Reply-To: <5480C336.8020901@multiplay.co.uk>
References:  <CACpH0Mc%2Bs9xwjNyrAPCh3%2BzxSAgr396h7jJGWxah7Zhx4CFyRg@mail.gmail.com> <5480C336.8020901@multiplay.co.uk>

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On 12/04/14 12:25, Steven Hartland wrote:
> If thats the case the underlying storage will be reporting a
> logical block size of 8k.
> 
> Assuming that's the case then this is expected / correct behavior.

It is: 8k is the default zvol blocksize.

BTW. Why bother to create zpools over zvols?  Wouldn't it mean double
checksumming?

Cheers,

> On 04/12/2014 19:05, Zaphod Beeblebrox wrote:
>> So... I think I answered at least a small part of my confusion
>> with the test ZFS datasets.  I created them with 'zpool create
>> vrx raidz /dev/zvol/*' ... and it would appear that the default
>> behavior for this is to assign ASHIFT to be 13 ... which makes
>> these test pools rater unrepresentative of ordinary zfs pools.
>> 
>> That means that many people using test ZFS pools are testing with
>> 8k blocks (not even just 4k blocks).  While I can immediately
>> understand what I need to do to get a representative test, I'm
>> posting because other people may have been similarly confused. 
>> _______________________________________________ 
>> freebsd-fs@freebsd.org mailing list 
>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs To
>> unsubscribe, send any mail to
>> "freebsd-fs-unsubscribe@freebsd.org"
> 
> _______________________________________________ 
> freebsd-fs@freebsd.org mailing list 
> http://lists.freebsd.org/mailman/listinfo/freebsd-fs To
> unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"


- -- 
Xin LI <delphij@delphij.net>    https://www.delphij.net/
FreeBSD - The Power to Serve!           Live free or die
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