Date: Mon, 30 Mar 2020 01:09:32 -0700 From: David Christensen <dpchrist@holgerdanske.com> To: freebsd-questions@freebsd.org Subject: Re: drive selection for disk arrays Message-ID: <4aef0358-b25a-028d-28ec-84fdabead8b7@holgerdanske.com> In-Reply-To: <ad2d65c8-b3ef-de46-42b6-102794c33a9d@holgerdanske.com> References: <20200325081814.GK35528@mithril.foucry.net> <713db821-8f69-b41a-75b7-a412a0824c43@holgerdanske.com> <20200326124648725158537@bob.proulx.com> <alpine.BSF.2.21.9999.2003261630030.47777@mail2.nber.org> <20200327104555.1d6d7cd9.freebsd@edvax.de> <1bcd7aa2-31e5-91f1-5151-926c9d16e16e@holgerdanske.com> <8e74482f-b951-ee97-50b8-04ea1f0d46a3@denninger.net> <ad2d65c8-b3ef-de46-42b6-102794c33a9d@holgerdanske.com>
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On 2020-03-27 18:46, David Christensen wrote: > On 2020-03-27 17:45, Karl Denninger wrote: >> >> On 3/27/2020 19:39, David Christensen wrote: >>> On 2020-03-27 02:45, Polytropon wrote: >>> >>>> When a drive _reports_ bad sectors, at least in the past >>>> it was an indication that it already _has_ lots of them. >>>> The drive's firmware will remap bad sectors to spare >>>> sectors, so "no error" so far. >>> >>> If a drive detects an error, my guess is that it will report the error >>> to the OS; regardless of the outcome of a particular I/O operation >>> (data read, data written, data lost) or internal actions taken (block >>> marked bad, block remapped, etc.). It is then up to the OS to decide >>> what to do next. RAID and/or ZFS offer the means for shielding the >>> application from I/O and drive failures. >>> >> Yes, but... >> >> Those drives that can do "SMART" will report (if you have a patrol >> daemon for it running) if they do a "silent" sector reassignment. >> Otherwise the OS is none the wiser and neither is ZFS (or anything >> else.) > > I guess I need to RTFM: > > https://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/serial-ata-ahci-spec-rev1-3-1.pdf That specification seems to address the HBA. It references the Serial ATA Revision 2.6 specification, which has been superseded. "SATA-IO" (consortium?) seems to control SATA specifications. "Serial ATA Revision 3.3 Specification (released February 2016)" is recommended for current implementations. It might contain the answers to our questions, but purchase is required: https://sata-io.org/developers/purchase-specification David
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