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Subject: RE: func spec for filesystem layout changes planned in zonda release
Date: Mon, 30 Jul 2007 09:54:23 -0700
Message-ID: <BB375AF679D4A34E9CA8DFA650E2B04E04AFB05B@onstor-exch02.onstor.net>
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Thread-Topic: func spec for filesystem layout changes planned in zonda release
Thread-Index: AcfOZ1fcj97QLA3/TZyOhVLcbCBEygEYUGuQ
References: <BB375AF679D4A34E9CA8DFA650E2B04E049DF422@onstor-exch02.onstor.net>
From: "Jonathan Goldick" <jonathan.goldick@onstor.com>
To: "Jobi Ariyamannil" <jobi.ariyamannil@onstor.com>,
	"dl-Design Review" <dl-designreview@onstor.com>

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1.	Section 5.2,

	a.	Is the only way to find the backup inodes to look in the
parentInum in the inode that is found to be corrupt?  This seems like a
risky place to put the recovery information since it only works if the
inode is mostly OK and only the emap is smashed.  I know that this is
the primary type of corruption you are concerned about but are there any
potential gains by putting it somewhere else?
	b.	Are these two new inodes snapable?
	c.	When we do a COW on the inode file and thereby change
it's emap will we also do a COW on the new inode?  Basically are we
going to completely duplicate all operations on the inode and gennum
inodes to their backups?

=20

________________________________

From: Jobi Ariyamannil=20
Sent: Tuesday, July 24, 2007 7:56 PM
To: dl-Design Review
Subject: func spec for filesystem layout changes planned in zonda
release

=20

Hi,

=20

Please review the attached func spec for filesystem layout changes
planned for zonda release.

Minor layout changes are made for additional hardening, availability,
recovery and tracing/debugging.

Please let me know any comments you may have.

=20

Regards,

Jobi


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 <li class=3DMsoNormal style=3D'color:navy;mso-list:l0 level1 =
lfo1'><font size=3D2
     color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial'>Section
     5.2,<o:p></o:p></span></font></li>
 <ol style=3D'margin-top:0in' start=3D1 type=3Da>
  <li class=3DMsoNormal style=3D'color:navy;mso-list:l0 level2 =
lfo1'><font size=3D2
      color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial'>Is
      the only way to find the backup inodes to look in the parentInum =
in the inode
      that is found to be corrupt? &nbsp;This seems like a risky place =
to put
      the recovery information since it only works if the inode is =
mostly OK
      and only the emap is smashed. &nbsp;I know that this is the =
primary type
      of corruption you are concerned about but are there any potential =
gains
      by putting it somewhere else?<o:p></o:p></span></font></li>
  <li class=3DMsoNormal style=3D'color:navy;mso-list:l0 level2 =
lfo1'><font size=3D2
      color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial'>Are
      these two new inodes snapable?<o:p></o:p></span></font></li>
  <li class=3DMsoNormal style=3D'color:navy;mso-list:l0 level2 =
lfo1'><font size=3D2
      color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial'>When
      we do a COW on the inode file and thereby change it&#8217;s emap =
will we
      also do a COW on the new inode? &nbsp;Basically are we going to
      completely duplicate all operations on the inode and gennum inodes =
to
      their backups?<o:p></o:p></span></font></li>
 </ol>
</ol>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

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<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> Jobi =
Ariyamannil
<br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Tuesday, July 24, =
2007 7:56
PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> func spec for =
filesystem
layout changes planned in zonda release</span></font><o:p></o:p></p>

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<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Hi,<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Please review the attached func spec for filesystem =
layout
changes planned for zonda release.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Minor layout changes are made for additional =
hardening,
availability, recovery and =
tracing/debugging.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Please let me know any comments you may =
have.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Regards,<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Jobi<o:p></o:p></span></font></p>

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