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rajarshi das

2006-Oct-17 15:13 UTC

[Xen-users] /home on domU

Hi,
   
  On SLES10, I have a separate /home partition on dom0 which is mounted read -
write.
  1) How do I mount a /home partition on domU? Do I need to create a file -
backed VBD?
   
  The second entry for disk=[ ''/dev/....'' ] in the sample
xmexample corresponds to /usr. How do I create a entry for /home?
   
  2) I created a file - backed VBD for the / partition on domU. Is it possible
to mount the / (root) partition of dom0 as root partition in domU, and be able
to write to it?
   
  Thanks in advance,
  Rajarshi

 		
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Sadique Puthen

2006-Oct-17 15:20 UTC

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Re: [Xen-users] /home on domU

rajarshi das wrote:> Hi,
>  
> On SLES10, I have a separate /home partition on dom0 which is mounted 
> read - write.
> 1) How do I mount a /home partition on domU? Do I need to create a 
> file - backed VBD?
>  
> The second entry for disk=[ ''/dev/....'' ] in the sample
xmexample
> corresponds to /usr. How do I create a entry for /home?You can use filebacked vbd, physical partitions or lvms - whatever you 
wish. Export that to Dom-U through its configuration file and mount it 
on the Dom-U.>  
> 2) I created a file - backed VBD for the / partition on domU. Is it 
> possible to mount the / (root) partition of dom0 as root partition in 
> domU, and be able to write to it?
>  You can do, but very dangerous. Exporting a filesystem which mounted 
read-write on Dom0 to a DomU read-write would corrupt the filesystem.  
You can do export it read-only which would be fine with
/usr.> Thanks in advance,
> Rajarshi
>
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Petersson, Mats

2006-Oct-17 15:27 UTC

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RE: [Xen-users] /home on domU

________________________________

	From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of rajarshi das
	Sent: 17 October 2006 16:14
	To: xen-users@lists.xensource.com
	Subject: [Xen-users] /home on domU

	Hi,

	On SLES10, I have a separate /home partition on dom0 which is
mounted read - write. 
	1) How do I mount a /home partition on domU? Do I need to create
a file - backed VBD? 

	The second entry for disk=[ ''/dev/....'' ] in the sample
xmexample corresponds to /usr. How do I create a entry for /home? 

I started by answering #2 below, but the answer here applies as well.
/usr/... is almost allways read-only (unless you''re instaling new
applications or something), so it''s feasible to mount this Read-Only
across multiple domains - if the file-system is read-only by all
clients, it''s fine to mount it multiple times from different places,
since the content isn''t going to chnge ... 

	2) I created a file - backed VBD for the / partition on domU. Is
it possible to mount the / (root) partition of dom0 as root partition in
domU, and be able to write to it?  

Not unless your Dom0-root is an NFS-mounted "partition" (and I doubt
that you''d use the word partition in that case). 

Any read-write mounted file-system needs to have ONE AND ONLY ONE
mountee - otherwise you''ll end up with a crashed file-system, because
there are BIG race-conditions that are cared for by locks inside the
file-system driver, but if you''re using two different file-system
drivers with different address spaces, that isn''t going to work. 

Read-only filesystems can be mounted multiple times, and there are
"special" file-systems that are capable of supporting multiple
clients,
but that''s not your average rootfs for Dom0... It''s either a
case of
"copy-on-write" implementations, or "cluser-file-system"
[which may be
COW-implementation, of course]. 

Filesystem choice is quite frequently discussed on this mailing list, so
searching the archive would probably give you more answers than you can
have questions... 
--
Mats

	Thanks in advance,
	Rajarshi

________________________________

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	Get on board. You''re invited
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rajarshi das

2006-Oct-18 05:47 UTC

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RE: [Xen-users] /home on domU

My query in << >>.

"Petersson, Mats" <Mats.Petersson@amd.com> wrote:       

      
---------------------------------
  From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of rajarshi das
Sent: 17 October 2006 16:14
To: xen-users@lists.xensource.com
Subject: [Xen-users] /home on domU


  
  Hi,
   
  On SLES10, I have a separate /home partition on dom0 which is mounted read -
write.
  1) How do I mount a /home partition on domU? Do I need to create a file -
backed VBD?
   
  The second entry for disk=[ ''/dev/....'' ] in the sample
xmexample corresponds to /usr. How do I create a entry for /home?
   
  I started by answering #2 below, but the answer here applies as well. /usr/...
is almost allways read-only (unless you''re instaling new applications
or something), so it''s feasible to mount this Read-Only across multiple
domains - if the file-system is read-only by all clients, it''s fine to
mount it multiple times from different places, since the content isn''t
going to chnge ...
  <<
  I created a file backed VBD for /home and added a entry in the configuration
file for domU as :
  disk = [ ''file:/root/rootdisk,sda2,w'' ] # this is the entry
for / partition. /dev/sda2 is my root partition on dom0.
  disk = [ ''file:/root/homedisk,sda3,w'' ] # Newly created
entry for /home.
   
  /dev/sda3 is my /home on dom0. 
   
  However, when I do a xm create with the above configuration, the root device
does not mount (which was mounting fine before adding an entry for /home
partition). Is this because the second entry is supposed to represent /usr (and
in my case it represents /home)?
  >>
     
   
   
  2) I created a file - backed VBD for the / partition on domU. Is it possible
to mount the / (root) partition of dom0 as root partition in domU, and be able
to write to it?
   
   
  Not unless your Dom0-root is an NFS-mounted "partition" (and I doubt
that you''d use the word partition in that case).
   
  Any read-write mounted file-system needs to have ONE AND ONLY ONE mountee -
otherwise you''ll end up with a crashed file-system, because there are
BIG race-conditions that are cared for by locks inside the file-system driver,
but if you''re using two different file-system drivers with different
address spaces, that isn''t going to work.
   
  Read-only filesystems can be mounted multiple times, and there are
"special" file-systems that are capable of supporting multiple
clients, but that''s not your average rootfs for Dom0... It''s
either a case of "copy-on-write" implementations, or
"cluser-file-system" [which may be COW-implementation, of course].
   
  Filesystem choice is quite frequently discussed on this mailing list, so
searching the archive would probably give you more answers than you can have
questions...
  --
  Mats
     
   
  Thanks in advance,
  Rajarshi
    
---------------------------------
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Get on board. You''re invited to try the new Yahoo! Mail.

 		
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Content-Transfer-Encoding: 8bit

My query in &lt;&lt;
&gt;&gt;.<BR><BR><B><I>"Petersson,
Mats" &lt;Mats.Petersson@amd.com&gt;</I></B> wrote: 
<BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px;
BORDER-LEFT: #1010ff 2px solid">  <META content="MSHTML
6.00.2900.2963" name=GENERATOR>  <DIV dir=ltr align=left><FONT
face=Arial color=#0000ff size=2></FONT>&nbsp;</DIV><BR>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT:
#0000ff 2px solid; MARGIN-RIGHT: 0px">  <DIV
class=OutlookMessageHeader lang=en-us dir=ltr align=left>  <HR
tabIndex=-1>  <FONT face=Tahoma size=2><B>From:</B>
xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] <B>On Behalf Of
</B>rajarshi das<BR><B>Sent:</B> 17 October 2006
16:14<BR><B>To:</B>
xen-users@lists.xensource.com<BR><B>Subject:</B> [Xen-users]
/home on domU<BR></FONT><BR></DIV> 
<DIV></DIV>  <DIV>Hi,</DIV> 
<DIV>&nbsp;</DIV>  <DIV>On SLES10, I have a separate /home
partition on dom0 which is mounted read - write.
 </DIV>  <DIV>1) How do I&nbsp;mount a /home partition on
domU?&nbsp;Do I need to create a file - backed VBD? </DIV> 
<DIV>&nbsp;</DIV>  <DIV>The second entry for disk=[
''/dev/....'' ] in the sample xmexample corresponds to /usr. How
do I create a entry for /home?<SPAN class=070181915-17102006><FONT
face=Arial color=#0000ff
size=2>&nbsp;</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN>&nbsp;</DIV></BLOCKQUOTE> 
<DIV><SPAN class=070181915-17102006><FONT face=Arial
color=#0000ff size=2>I started by answering #2 below, but the answer here
applies as well. /usr/... is almost allways read-only (unless you''re
instaling new applications or something), so it''s feasible to mount
this Read-Only across multiple domains - if the file-system is read-only by all
clients, it''s fine to mount it multiple times from different places,
since the content isn''t going to chnge ...
</FONT></SPAN></DIV>  <DIV><SPAN
 class=070181915-17102006><FONT
color=#0000ff>&lt;&lt;</FONT></SPAN></DIV> 
<DIV><SPAN class=070181915-17102006><FONT color=#00007f>I
created a file backed VBD for /home and added a entry in the configuration file
for domU as :</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT color=#00007f>disk = [
''file:/root/rootdisk,sda2,w'' ] # this is the entry for /
partition. /dev/sda2 is my root partition on
dom0.</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT color=#00007f><STRONG>disk = [
''file:/root/homedisk,sda3,w'' ]</STRONG> # Newly created
entry for /home.</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT
color=#00007f></FONT></SPAN>&nbsp;</DIV> 
<DIV><SPAN class=070181915-17102006><FONT
color=#00007f>/dev/sda3 is my /home on dom0.
</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT
color=#00007f></FONT></SPAN>&nbsp;</DIV> 
<DIV><SPAN class=070181915-17102006><FONT
color=#00007f>However, when I do a xm create with the above
 configuration, the root device does not mount (which was mounting fine before
adding an entry for /home partition). Is this because the second entry is
supposed to represent /usr (and in my case it represents /home)?
</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT
color=#00007f>&gt;&gt;</FONT></SPAN></DIV> 
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT:
#0000ff 2px solid; MARGIN-RIGHT: 0px">  <DIV><SPAN
class=070181915-17102006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN>&nbsp;</DIV>  <DIV><SPAN
class=070181915-17102006></SPAN>&nbsp;</DIV> 
<DIV>&nbsp;</DIV>  <DIV>2) I created a file - backed VBD
for the / partition on domU. Is it possible to mount the / (root) partition of
dom0 as root partition in domU, and be able to write to it?&nbsp;<SPAN
class=070181915-17102006><FONT face=Arial color=#0000ff
size=2>&nbsp;</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006></SPAN>&nbsp;</DIV> 
<DIV><SPAN
 class=070181915-17102006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN>&nbsp;</DIV></BLOCKQUOTE> 
<DIV><SPAN class=070181915-17102006><FONT face=Arial
color=#0000ff size=2>Not unless your Dom0-root is an NFS-mounted
"partition" (and I doubt that you''d use the word partition in
that case). </FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN>&nbsp;</DIV>  <DIV><SPAN
class=070181915-17102006><FONT face=Arial color=#0000ff size=2>Any
read-write mounted file-system needs to have ONE AND ONLY ONE mountee -
otherwise you''ll end up with a crashed file-system, because there are
BIG race-conditions that are cared for by locks inside the file-system driver,
but if you''re using two different file-system drivers with different
address spaces, that isn''t going to work.
</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN>&nbsp;</DIV>  <DIV><SPAN
 class=070181915-17102006><FONT face=Arial color=#0000ff
size=2>Read-only filesystems can be mounted multiple times, and there are
"special" file-systems that are capable of supporting multiple
clients, but that''s not your average rootfs for Dom0... It''s
either a case of "copy-on-write" implementations, or
"cluser-file-system" [which may be COW-implementation, of course].
</FONT></SPAN></DIV>  <DIV><SPAN
class=070181915-17102006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN>&nbsp;</DIV>  <DIV><FONT
face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=070181915-17102006>Filesystem choice is quite frequently discussed on
this mailing list, so searching the archive would probably give you more answers
than you can have questions...
</SPAN></FONT></FONT></FONT></DIV> 
<DIV><SPAN class=070181915-17102006><FONT face=Arial
color=#0000ff size=2>--</FONT></SPAN></DIV> 
<DIV><SPAN class=070181915-17102006><FONT face=Arial
color=#0000ff size=2>Mats</FONT></SPAN></DIV>
 <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT:
#0000ff 2px solid; MARGIN-RIGHT: 0px">  <DIV><SPAN
class=070181915-17102006></SPAN>&nbsp;</DIV> 
<DIV>&nbsp;</DIV>  <DIV>Thanks in advance,</DIV> 
<DIV>Rajarshi</DIV>  <div>  <HR SIZE=1>  Do you
Yahoo!?<BR>Get on board. <A
href="http://us.rd.yahoo.com/evt=40791/*http://advision.webevents.yahoo.com/mailbeta">You''re
invited</A> to try the new Yahoo!
Mail.</BLOCKQUOTE></BLOCKQUOTE><BR><p>&#32;
		<hr size=1>How low will we go? Check out Yahoo! Messengers low <a
href="http://us.rd.yahoo.com/mail_us/taglines/postman8/*http://us.rd.yahoo.com/evt=39663/*http://voice.yahoo.com">
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Ulrich Windl

2006-Nov-14 07:38 UTC

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Re: [Xen-users] /home on domU

He sent the question to the wrong person ;-)

On 13 Nov 2006 at 20:35, rajarshi das wrote:
> Hi,
>    
>   A couple of questions:
>    
>   1) Is your NFS exported /home mounted rw on all your domUs?
>   2) Is it possible to have the NFS server inside dom0 and export it such
that all domUs can access the same NFS mount rw?
>    
>   Appreciate if you can send your domU configuration which accesses the NFS
mount rw.
>    
>   Thanks in advance,
>   Rajarshi
> 
> Ulrich Windl <ulrich.windl@rz.uni-regensburg.de> wrote:
>   On 17 Oct 2006 at 8:13, rajarshi das wrote:
> 
> > Hi,
> > 
> > On SLES10, I have a separate /home partition on dom0 which is mounted
read - write.
> > 1) How do I mount a /home partition on domU? Do I need to create a
file - backed VBD?
> 
> Do your "normal users" work in Dom0? Here we have an NFS exported
/home (NFS
> Server outside XEN), and you can mount it in any DomU (and Dom0), but we
don''t
> configure normal users for Dom0.
> 
> [...]
> 
> Regards,
> Ulrich
> 
> 
> 
>  
> ---------------------------------
> Want to start your own business? Learn how on Yahoo! Small Business.


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Jerry Amundson

2006-Nov-14 19:41 UTC

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Re: [Xen-users] /home on domU

> On 13 Nov 2006 at 20:35, rajarshi das wrote:
> > Hi,
> >
> >   A couple of questions:
> >
> >   1) Is your NFS exported /home mounted rw on all your domUs?
> >   2) Is it possible to have the NFS server inside dom0 and export it
such that all domUs can access the same NFS mount rw?
The NFS mailing list is the second door down, on the left... ;-)

jerry

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Xen users - Oct 2006 - /home on domU

[Xen-users] /home on domU

Re: [Xen-users] /home on domU

RE: [Xen-users] /home on domU

RE: [Xen-users] /home on domU

Re: [Xen-users] /home on domU

Re: [Xen-users] /home on domU