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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Most of the MegaRaid cards I’ve seen are made by LSI/Avago (including the Dell PERC/SAS which are OEMed from LSI/Avago).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">During POST when it find the BIOS of these cards it usually gives you a Ctrl-R option to go into that for config. I don’t know whether that config allows
you to change individual drive cache setup. Typically I don’t muck with such setups on the assumption the card was already optimized. I’ve only used it for creating/modifying the RAID layout.
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Once they’re in a RAID presented by the card you’re not going to see the individual drives at OS level – you’ll just see the entire RAID set(s) as individual
drive(s). e.g. If you had created a RAID1 of 2 disks for OS then a RAID5 for remaining disks you’re only going to see /dev/sda and /dev/sdb at OS level.<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> ale-bounces@ale.org [mailto:ale-bounces@ale.org]
<b>On Behalf Of </b>Jim Kinney<br>
<b>Sent:</b> Friday, September 02, 2016 4:13 PM<br>
<b>To:</b> Atlanta Linux Enthusiasts - Yes! We run Linux!<br>
<b>Subject:</b> [ale] hdparm and RAID cards<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">How the $(^*#!!! do I use hdparm to enable write caching on a giant pile of drives that make up a hardware RAID 6 array?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I can peek through the controller with smartctl for health monitoring. The RAID controller (MegaRAID) has a tool to see that each drive has a N/A status for hardware cache (these drives all have a large multi-MB cache).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I _really_ don't want to have to convert all 28 drives to RAID0 so I can get a /dev/sdx node for hdparm.<o:p></o:p></p>
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<pre>-- <o:p></o:p></pre>
<pre>James P. Kinney III<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>Every time you stop a school, you will have to build a jail. What you<o:p></o:p></pre>
<pre>gain at one end you lose at the other. It's like feeding a dog on his<o:p></o:p></pre>
<pre>own tail. It won't fatten the dog.<o:p></o:p></pre>
<pre>- Speech 11/23/1900 Mark Twain<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre><a href="http://heretothereideas.blogspot.com/">http://heretothereideas.blogspot.com/</a><o:p></o:p></pre>
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