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<TITLE>AW: AW: RAID greater than 2TB on Fedora Core 3</TITLE>
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<P><FONT SIZE=2>hello rick, </FONT>
</P>
<P><FONT SIZE=2>first thanks a lot for this detailed explaination!</FONT>
</P>
<P><FONT SIZE=2>but (maybe stupid...), if it's possible to configure</FONT>
<BR><FONT SIZE=2>the blocksize of my raid, it should be possible to access</FONT>
<BR><FONT SIZE=2>greater raids than 2TB, right?</FONT>
</P>
<P><FONT SIZE=2>thanks,</FONT>
<BR><FONT SIZE=2>christian </FONT>
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<P><FONT SIZE=2>-----Ursprüngliche Nachricht-----</FONT>
<BR><FONT SIZE=2>Von: fedora-list-bounces@redhat.com [<A HREF="mailto:fedora-list-bounces@redhat.com">mailto:fedora-list-bounces@redhat.com</A>] Im Auftrag von Rick Stevens</FONT>
<BR><FONT SIZE=2>Gesendet: Montag, 04. April 2005 22:08</FONT>
<BR><FONT SIZE=2>An: For users of Fedora Core releases</FONT>
<BR><FONT SIZE=2>Betreff: Re: AW: RAID greater than 2TB on Fedora Core 3</FONT>
</P>
<P><FONT SIZE=2>Masopust Christian wrote:</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Hi Rick,</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> is it really (nowadays??) a problem of SCSI-controler?</FONT>
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<P><FONT SIZE=2>No, it's the SCSI protocol. SCSI allows 4 bytes (32 bits) to specify</FONT>
<BR><FONT SIZE=2>the block number on a device, or 4,394,957,296 blocks. Given that most</FONT>
<BR><FONT SIZE=2>disks use a 512-byte block, that's:</FONT>
</P>
<P> <FONT SIZE=2>4,394,957,269 * 512 = 2,199,023,255,552 bytes</FONT>
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<P><FONT SIZE=2>or 2TB. And before people jump on me, it's an unsigned 4-byte block</FONT>
<BR><FONT SIZE=2>number. A signed value would make no sense--how do you access a</FONT>
<BR><FONT SIZE=2>negative block number? I hear that the latest SCSI spec addresses this,</FONT>
<BR><FONT SIZE=2>but I have no idea when (or if) it will be released and how long the</FONT>
<BR><FONT SIZE=2>manufacturers will take to implement the new spec (if ever).</FONT>
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<P><FONT SIZE=2>As an aside, the old 2GB file size limit was caused by using a signed</FONT>
<BR><FONT SIZE=2>32-bit value as the second parameter in an lseek() (2^31 is</FONT>
<BR><FONT SIZE=2>2,147,483,648, and that's in bytes--not blocks and it was signed to</FONT>
<BR><FONT SIZE=2>allow you to seek backwards from the current postition).</FONT>
<BR><FONT SIZE=2>----------------------------------------------------------------------</FONT>
<BR><FONT SIZE=2>- Rick Stevens, Senior Systems Engineer rstevens@vitalstream.com -</FONT>
<BR><FONT SIZE=2>- VitalStream, Inc. <A HREF="http://www.vitalstream.com" TARGET="_blank">http://www.vitalstream.com</A> -</FONT>
<BR><FONT SIZE=2>- -</FONT>
<BR><FONT SIZE=2>- This message printed using recycled bandwidth -</FONT>
<BR><FONT SIZE=2>----------------------------------------------------------------------</FONT>
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