<div>On Wed, Oct 28, 2009 at 01:10, Peter O'Gorman <span dir="ltr"><<a href="mailto:peter@pogma.com">peter@pogma.com</a>></span> wrote:</div><blockquote class="gmail_quote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex; ">
On 10/27/2009 09:38 PM, Adam Thompson wrote:<br>> reallocate bad sectors on WRITE, and *not* on read. The *destructive*<br>> SMART "Long" test causes every sector to be re-written, which will<br>I don't believe the SMART long test is destructive, why do you think so?<br>
</blockquote><div><br></div>Sorry, I wasn't clear enough in my original posting.<div><br></div><div>The regular SMART "Long" test is *not* destructive.</div><div><br></div><div>Some HDDs - there's no pattern than I can discern to tell which, other than reading the documentation - offer an additional, *non-standard* destructive test. Some of *those* HDDs appear to invoke the same function as "low-level format", since both are essentially equivalent processes. Sector remapping takes place as usual during either command.</div>
<div><br></div><div>Generally speaking, SCSI, FC and SAS devices should always support a low-level format command, per ANSI T13. IDE and SATA devices may or may not support a low-level format command. The SMART specification (per ANSI T13) is extensible, and specifies a *minimum* level of functionality; some vendors - at least in certain models - implement more than minimum required functionality. It seems to me that models sold as OEM equipment to server and storage appliance vendors often implement extra functionality, probably at the request of vendors like NetApp, EMC, Dell, HP, etc. Since most storage vendors now offer cheap(er) SATA storage options for their arrays, some so-called "desktop" models will also benefit from this.</div>
<div><br>The only way to be certain is to read the technical documentation for your particular drive, which will tell you precisely what commands the drive supports. I'm not talking about the user manual; note that some drives do not appear to have any such documentation - in which case you can probably assume they don't support anything beyond the minimum required feature set.</div>
<div><br>-- <br>-Adam Thompson<br> <<a href="mailto:athompso@athompso.net">athompso@athompso.net</a>><br><br>
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