<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><html>On Apr 11, 2008, at 9:18 AM, Luca Berra wrote:</html><blockquote type="cite">this is not entirely correct.<br>md has a bitmap feature that is used to track which blocks are out of<br>sync.</blockquote>For the record, this is called a "write-intent bitmap". It's very handy, although to make it really perform you need to put it on a separate spindle from the data (which is supported). Otherwise the extra seeks cause quite an impact on disk performance.</div><div><br></div><br><br><div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div>-- </div><div>Jayson Vantuyl</div><div><font class="Apple-style-span" size="2"><span class="Apple-style-span" style="font-size: 10px; "><span class="Apple-style-span" style="font-size: 10px; "><span class="Apple-style-span" style="font-size: 10px; ">Systems Architect</span></span></span></font></div><div><b style="font-weight: bold; "><a href="http://www.engineyard.com"><span class="Apple-style-span" style="font-weight: normal; color: rgb(0, 0, 238); -webkit-text-decorations-in-effect: underline; "><span class="Apple-style-span" style="color: rgb(0, 0, 238); -webkit-text-decorations-in-effect: underline; ">Engine Yard</span></span></a></b></div><div><font class="Apple-style-span" size="2"><span class="Apple-style-span" style="font-size: 10px; "><span class="Apple-style-span" style="font-size: 10px; "><span class="Apple-style-span" style="font-size: 10px; "><a href="mailto:jvantuyl@engineyard.com">jvantuyl@engineyard.com</a></span></span></span></font></div><div><font class="Apple-style-span" size="2"><span class="Apple-style-span" style="font-size: 10px; ">1 866 518 9275 ext 204</span></font></div></span></span></div></span></div></span></div></span> </div><br></body></html>