<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:p="urn:schemas-microsoft-com:office:powerpoint" xmlns:a="urn:schemas-microsoft-com:office:access" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882" xmlns:rs="urn:schemas-microsoft-com:rowset" xmlns:z="#RowsetSchema" xmlns:b="urn:schemas-microsoft-com:office:publisher" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:c="urn:schemas-microsoft-com:office:component:spreadsheet" xmlns:odc="urn:schemas-microsoft-com:office:odc" xmlns:oa="urn:schemas-microsoft-com:office:activation" xmlns:html="http://www.w3.org/TR/REC-html40" xmlns:q="http://schemas.xmlsoap.org/soap/envelope/" xmlns:rtc="http://microsoft.com/officenet/conferencing" xmlns:D="DAV:" xmlns:Repl="http://schemas.microsoft.com/repl/" xmlns:mt="http://schemas.microsoft.com/sharepoint/soap/meetings/" xmlns:x2="http://schemas.microsoft.com/office/excel/2003/xml" xmlns:ppda="http://www.passport.com/NameSpace.xsd" xmlns:ois="http://schemas.microsoft.com/sharepoint/soap/ois/" xmlns:dir="http://schemas.microsoft.com/sharepoint/soap/directory/" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:dsp="http://schemas.microsoft.com/sharepoint/dsp" xmlns:udc="http://schemas.microsoft.com/data/udc" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:sub="http://schemas.microsoft.com/sharepoint/soap/2002/1/alerts/" xmlns:ec="http://www.w3.org/2001/04/xmlenc#" xmlns:sp="http://schemas.microsoft.com/sharepoint/" xmlns:sps="http://schemas.microsoft.com/sharepoint/soap/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:udcs="http://schemas.microsoft.com/data/udc/soap" xmlns:udcxf="http://schemas.microsoft.com/data/udc/xmlfile" xmlns:udcp2p="http://schemas.microsoft.com/data/udc/parttopart" xmlns:wf="http://schemas.microsoft.com/sharepoint/soap/workflow/" xmlns:dsss="http://schemas.microsoft.com/office/2006/digsig-setup" xmlns:dssi="http://schemas.microsoft.com/office/2006/digsig" xmlns:mdssi="http://schemas.openxmlformats.org/package/2006/digital-signature" xmlns:mver="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns:mrels="http://schemas.openxmlformats.org/package/2006/relationships" xmlns:spwp="http://microsoft.com/sharepoint/webpartpages" xmlns:ex12t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:ex12m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:pptsl="http://schemas.microsoft.com/sharepoint/soap/SlideLibrary/" xmlns:spsl="http://microsoft.com/webservices/SharePointPortalServer/PublishedLinksService" xmlns:Z="urn:schemas-microsoft-com:" xmlns:st="" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:"Trebuchet MS";
panose-1:2 11 6 3 2 2 2 2 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:"Sans Serif";
panose-1:0 0 0 0 0 0 0 0 0 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
h1
{mso-style-priority:9;
mso-style-link:"Heading 1 Char";
margin-top:24.0pt;
margin-right:0cm;
margin-bottom:0cm;
margin-left:0cm;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:10.0pt;
font-family:"Trebuchet MS","sans-serif";}
h2
{mso-style-priority:9;
mso-style-link:"Heading 2 Char";
margin-top:10.0pt;
margin-right:0cm;
margin-bottom:0cm;
margin-left:0cm;
margin-bottom:.0001pt;
page-break-after:avoid;
font-size:10.0pt;
font-family:"Trebuchet MS","sans-serif";}
p.MsoTitle, li.MsoTitle, div.MsoTitle
{mso-style-priority:10;
mso-style-link:"Title Char";
margin-top:0cm;
margin-right:0cm;
margin-bottom:15.0pt;
margin-left:0cm;
border:none;
padding:0cm;
font-size:12.0pt;
font-family:"Trebuchet MS","sans-serif";
letter-spacing:.25pt;
font-weight:bold;}
p.MsoTitleCxSpFirst, li.MsoTitleCxSpFirst, div.MsoTitleCxSpFirst
{mso-style-priority:10;
mso-style-link:"Title Char";
mso-style-type:export-only;
margin:0cm;
margin-bottom:.0001pt;
border:none;
padding:0cm;
font-size:12.0pt;
font-family:"Trebuchet MS","sans-serif";
letter-spacing:.25pt;
font-weight:bold;}
p.MsoTitleCxSpMiddle, li.MsoTitleCxSpMiddle, div.MsoTitleCxSpMiddle
{mso-style-priority:10;
mso-style-link:"Title Char";
mso-style-type:export-only;
margin:0cm;
margin-bottom:.0001pt;
border:none;
padding:0cm;
font-size:12.0pt;
font-family:"Trebuchet MS","sans-serif";
letter-spacing:.25pt;
font-weight:bold;}
p.MsoTitleCxSpLast, li.MsoTitleCxSpLast, div.MsoTitleCxSpLast
{mso-style-priority:10;
mso-style-link:"Title Char";
mso-style-type:export-only;
margin-top:0cm;
margin-right:0cm;
margin-bottom:15.0pt;
margin-left:0cm;
border:none;
padding:0cm;
font-size:12.0pt;
font-family:"Trebuchet MS","sans-serif";
letter-spacing:.25pt;
font-weight:bold;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.MsoNoSpacing, li.MsoNoSpacing, div.MsoNoSpacing
{mso-style-priority:1;
margin:0cm;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Trebuchet MS","sans-serif";}
span.Heading1Char
{mso-style-name:"Heading 1 Char";
mso-style-priority:9;
mso-style-link:"Heading 1";
font-family:"Trebuchet MS","sans-serif";
font-weight:bold;}
span.Heading2Char
{mso-style-name:"Heading 2 Char";
mso-style-priority:9;
mso-style-link:"Heading 2";
font-family:"Trebuchet MS","sans-serif";
font-weight:bold;}
span.TitleChar
{mso-style-name:"Title Char";
mso-style-priority:10;
mso-style-link:Title;
font-family:"Trebuchet MS","sans-serif";
letter-spacing:.25pt;
font-weight:bold;}
span.EmailStyle22
{mso-style-type:personal-reply;
font-family:"Tahoma","sans-serif";
color:blue;
font-weight:normal;
font-style:normal;
text-decoration:none none;}
.MsoChpDefault
{mso-style-type:export-only;}
@page Section1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.Section1
{page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=EN-NZ link=blue vlink=purple>
<div class=Section1>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";
color:blue'>Thanks Steve. RAID1 with LVM will give me what I need, I was just
hoping for RAID 1+0 so I could also get the performance gain, which may be
handy if I end up with three frontends all watching and recording HD at the
same time. If I had three RAID1 arrays as per Tim’s email, and then put
RAID0 over the top, could I subsequently add in another RAID1 pair as per Tim’s
directions, and then grow the RAID0 across the extra RAID1 pair without having
to backup? I guess in short I’m asking can you currently add disks/partitions
to a RAID0 automatically without loss of data? I find many conflicting answers
on the net.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";
color:blue'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>
<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> mythtvnz-bounces@lists.linuxnut.co.nz
[mailto:mythtvnz-bounces@lists.linuxnut.co.nz] <b>On Behalf Of </b>Steve Hodge<br>
<b>Sent:</b> Thursday, 18 June 2009 12:19 p.m.<br>
<b>To:</b> MythTV in NZ<br>
<b>Subject:</b> Re: [mythtvnz] File System for RAID-5<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<p class=MsoNormal>On Thu, Jun 18, 2009 at 6:47 AM, James Booth <<a
href="mailto:james@booths.net.nz">james@booths.net.nz</a>> wrote:<o:p></o:p></p>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Sans Serif","serif"'><br>
I've set up a trial RAID 1+0 using Tim's layout as below, and it's all fine. I
have one last question.<br>
<br>
Tim, using your setup, if I am running RAID 1+0 then will it be possible to add
another disk later on without having to back all the data up first? (I'd try
it, but don't have a spare disk to hand). Could I add in drive D as per your
example, and then automatically grow the RAID 0 across the top? I have not been
able to find a definitive answer on this on the net.<br>
<br>
Same goes for RAID10,F2 - if I go this route can I just automatically grow the
system with an extra disk later on?<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><br>
As far as I know you can't grow raid10 arrays. It's been on the todo list for
at least a couple of years but I haven't found anything to indicate that it's
been implemented. Personally I've found that by the time I want to expand an
array the best value disks are significantly larger than the disks in the
array. So a simple expand would leave me with part of the new disk left over.
So I find I want to either rebuild from scratch anyway or setup the new disk in
a second array. Usually if I think about it long enough I can figure out a way
to add the new drive without having to back anything up by degrading the
existing array to free up space.<br>
<br>
Here's an example of the sort of thing I've done in the past: Say I started
with 3 500GB drives in a raid10 (A, B, and C, total size 750GB). I buy a new
1000GB drive (D). I partition the new drive into 2 500GB partitions - you
really need to be dealing with equal sized partitions. I can't make a single
raid10 out of the 5 500GB partitions unless I set it up with 3 copies of
everything because if there are only two copies then some blocks will have
their two copies on D1 and D2 which is not safe. Of course if I rebuilt the
whole array I'd have to find temporary space for 750GB of data and I don't have
that available anyway. So what I do instead is to replace one of the existing
partitions in the raid10 with one of the new partitions:<br>
1. degrade the array by removing (say) A.<br>
2. add D1 to the array and let it resync.<br>
Now I have A and D2 to make a raid1. I can either use that as a separate
filesystem or, if I was using LVM over the original array I can combine the two
arrays that way.<br>
<br>
There are two obvious alternatives to this sort of thing. First, you could use
raid5 which is growable. Just be aware that it degrades to a raid0 - I don't
recommend expanding a raid5 beyond about 4 disks. If you're expecting to end up
with more than that then raid6 would be a safer option. The second alternative
is to always expand by pairs of disks. If you do that then it's trivial to set
up new raid1 mirrors and combine them with existing arrays using LVM.<br>
<br>
Cheers,<br>
Steve<o:p></o:p></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
</div>
</body>
</html>