Date: Thu, 24 Jan 2013 22:46:37 +0200 From: Daniel Kalchev <daniel@digsys.bg> To: Borja Marcos <borjam@sarenet.es> Cc: FreeBSD Filesystems <freebsd-fs@freebsd.org>, freebsd-scsi@freebsd.org Subject: Re: Problem adding SCSI quirks for a SSD, 4K sector and ZFS Message-ID: <92BD25C7-FC6C-41AF-80AE-05AAD4CD4659@digsys.bg> In-Reply-To: <FF2FCD9E-0CA5-4030-8881-C866FA97CF1D@sarenet.es> References: <492280E6-E3EE-4540-92CE-C535C8943CCF@sarenet.es> <A71C9D2FA3984F6A84CED6DE3E21DDCF@multiplay.co.uk> <FF2FCD9E-0CA5-4030-8881-C866FA97CF1D@sarenet.es>
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On Jan 24, 2013, at 6:09 PM, Borja Marcos <borjam@sarenet.es> wrote: > Oh, sorrry for the confusion! I assumed that the da driver would announce a 4 KB sector instead of the 512 bytes due to the quirks. > > Which brings an interesting question, I might have a potential time bomb in my experimental machine at home. It's a ZFS mirror with two 500 MB disks. One of the has 512 byte sectors, the other is "advanced format". If you did not create your zpool with ashift=12, then you have the bomb already. Disks with different native sector size coexist quite happily in the same zpool. If the storage does not lie, ZFS will in fact use the largest 'sector size' and everything will be ok. Many (most) advanced format drives however lie about their sector size and pretend to have 512 byte sectors. If you create an zpool with such a drive and an 'normal' 512 byte drive without explicitly requesting 4k alignment, thing are bad. Daniel
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