> -----Original Message----- > From: OmniOS-discuss [mailto:omnios-discuss-boun...@lists.omniti.com] On > Behalf Of Chris Siebenmann > Sent: 星期二, 三月 22, 2016 3:27 > To: Richard Elling > Cc: omnios-discuss@lists.omniti.com > Subject: Re: [OmniOS-discuss] 4kn or 512e with ashift=12 > > > > Adding the ashift argument to zpool was discussed every few years > > > and so far was always deemed not enterprisey enough for the Solaris > > > heritage, so the setup to tweak sd driver reports and properly rely > > > on that layer was pushed instead. > > > > The issue is that once a drive model lies, then the Solaris approach > > is to encode the lie into a whitelist, so that the lie is always > > handled properly. The whitelist is in the sd.conf file. > > > > By contrast, the ZFSonLinux approach requires that the sysadmin knows > > there is a lie and manually corrects for every invocation. This is > > unfortunately a very error-prone approach. > > This implicitly assumes that the only reason to set ashift=12 is if you are > currently using one or more drives that require it. I strongly disagree with > this > view. Since ZFS cannot currently replace a 512n drive with a 512e one, I feel
*In theory* this replacement should work well if the lie works *correctly*. In ZoL, for the "-o ashift" is supported in "zpool replace", the replacement should also work in mixed sector sizes. And in illumos the whitelist will do the same. What errors have you ever seen? > that you really want to force-create all pools with ashift=12 even on 512n > drives > unless you're absolutely confident that you will be able to obtain replacement > 512n drives over the lifetime of your pool (or unless the impact of using > ashift=12 is so drastic on your usage case that you will need to totally > rethink > your pool if you become unable to get 512n replacement drives). Same as my comments above. > > For many usage cases, somewhat more space usage and perhaps somewhat > slower pools are vastly preferable to a loss of pool redundancy over time. I > feel > that OmniOS should at least give you the option here (in a less crude way than > simply telling it that absolutely all of your drives are 4k drives, partly > because > such general lies are problematic in various situations). > The whitelist (sd.conf) should fit into this consideration. But not sure how mixed sector sizes impact the performance. Thanks. Fred _______________________________________________ OmniOS-discuss mailing list OmniOS-discuss@lists.omniti.com http://lists.omniti.com/mailman/listinfo/omnios-discuss