Date: Fri, 21 Nov 1997 08:22:28 +1030 From: Mike Smith <mike@smith.net.au> To: Charles Mott <cmott@srv.net> Cc: freebsd-hardware@freebsd.org Subject: Re: large IDE disks Message-ID: <199711202152.IAA00343@word.smith.net.au> In-Reply-To: Your message of "Thu, 20 Nov 1997 12:33:32 PDT." <Pine.BSF.3.96.971120123115.6628B-100000@darkstar.home>
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> > The drives should remap bad sectors by themselves, if that fails it has > > no more spares, and are now "junk drives" (those some of the more > > "ingenious" dealers try to sell anyways)... Use your 3 year warranty > > to get it replaced ASAP. > > Are the bad sectors determined at the time of manufactruing or does the > drive somehow automatically do this when it is reformatted? The drive is "formatted" at manufacture time. You can't (generally) "reformat" an IDE disk without using a vendor-specific tool. Part of the formatting process sets aside sections of the disk as "spare". When a region fails, accesses to the failing region are forwarded to a replacement area from the spare region. > Mainly, I am wondering whether the drives can automatically deal with new > bad sectors as they appear. This should be obvious from Soren's statement, but to clarify: yes, all modern disks (IDE and SCSI) should be capable of remapping bad sectors on the fly. Note that SCSI disks generally offer options controlling this behaviour; see the example in the scsi(8) manpage for details on how to edit mode page 4, which contains the ARRE (reallocate on recovered read error) and AWRE (reallocate on write error) flags. Note that if ARRE is set and the contents of the sector cannot be recovered, a hard error will be reported. The only way then to force the sector to be reallocated is to write to it. mike
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