How to share filesystem

How to share filesystem

[Ross Boylan]

I would like to have access to the same file system from the host and
the guest.  Can anyone recommend the best way to do this, considering
ease of use, safety (concurrent access from guest and host does not
corrupt) and performance?

For example, I would like to restore files from backup using the host,
but write to filesystems used by the guest.

I have previously used kvm mostly with disks that are based on LVM
logical volumes, e.g. -hda /dev/turtle/Squeeze00.  Since the LVs are
virtual disks, I can't just mount them in the host AFAIK.

Among the alternatives I can think of are using NFS and using NBD.
Maybe there's some kind of loopback device I could use on the disk image
to access it from the host.

Host: Debian GNU/Linux wheezy, amd64 architecture, qemu-kvm 1.1.2
Guest: Debian GNU/Linux lenny i386.
Host processor is a recent i5 with good virtualization (flaga: fpu vme
de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush
dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm
constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc
aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3
cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes
xsave avx f16c rdrand lahf_lm ida arat epb xsaveopt pln pts dtherm
tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms)

Thanks.
Ross Boylan

Re: How to share filesystem

[Thomas Huth]

Am Tue, 24 Sep 2013 01:38:39 -0700
schrieb Ross Boylan <ross@biostat.ucsf.edu>:

> I would like to have access to the same file system from the host and
> the guest.  Can anyone recommend the best way to do this, considering
> ease of use, safety (concurrent access from guest and host does not
> corrupt) and performance?
[...]
> Among the alternatives I can think of are using NFS and using NBD.
> Maybe there's some kind of loopback device I could use on the disk image
> to access it from the host.

I've never tried it on my own, but there is also virtio-9p:

 http://wiki.qemu.org/Documentation/9psetup

Maybe that's what you need?

 Thomas

RE: How to share filesystem

[P Balaji-B37839]

You can as well try Qemu-GuestAgent which uses Virtio-Serial communication for Guest and Host.

-----Original Message-----
From: kvm-owner@vger.kernel.org [mailto:kvm-owner@vger.kernel.org] On Behalf Of Thomas Huth
Sent: Tuesday, September 24, 2013 3:54 PM
To: Ross Boylan
Cc: kvm@vger.kernel.org
Subject: Re: How to share filesystem

Am Tue, 24 Sep 2013 01:38:39 -0700
schrieb Ross Boylan <ross@biostat.ucsf.edu>:

> I would like to have access to the same file system from the host and 
> the guest.  Can anyone recommend the best way to do this, considering 
> ease of use, safety (concurrent access from guest and host does not
> corrupt) and performance?
[...]
> Among the alternatives I can think of are using NFS and using NBD.
> Maybe there's some kind of loopback device I could use on the disk 
> image to access it from the host.

I've never tried it on my own, but there is also virtio-9p:

 http://wiki.qemu.org/Documentation/9psetup

Maybe that's what you need?

 Thomas

--
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Re: How to share filesystem

[Ross Boylan]

On Tue, 2013-09-24 at 12:24 +0200, Thomas Huth wrote:
> Am Tue, 24 Sep 2013 01:38:39 -0700
> schrieb Ross Boylan <ross@biostat.ucsf.edu>:
> 
> > I would like to have access to the same file system from the host and
> > the guest.  Can anyone recommend the best way to do this, considering
> > ease of use, safety (concurrent access from guest and host does not
> > corrupt) and performance?
> [...]
> > Among the alternatives I can think of are using NFS and using NBD.
> > Maybe there's some kind of loopback device I could use on the disk image
> > to access it from the host.
> 
> I've never tried it on my own, but there is also virtio-9p:
> 
>  http://wiki.qemu.org/Documentation/9psetup
> 
> Maybe that's what you need?
> 
>  Thomas
> 
At first I saw Plan 9 and figured it was irrelevant to linux, but the
example seems to be Linux.  So I'm puzzled.
Ross

Re: How to share filesystem

[shendl1978]

You。can use. Virtio-9p.  In. Linux.

发自我的 iPhone

> 在 2013年9月25日，0:37，Ross Boylan <ross@biostat.ucsf.edu> 写道：
> 
>> On Tue, 2013-09-24 at 12:24 +0200, Thomas Huth wrote:
>> Am Tue, 24 Sep 2013 01:38:39 -0700
>> schrieb Ross Boylan <ross@biostat.ucsf.edu>:
>> 
>>> I would like to have access to the same file system from the host and
>>> the guest.  Can anyone recommend the best way to do this, considering
>>> ease of use, safety (concurrent access from guest and host does not
>>> corrupt) and performance?
>> [...]
>>> Among the alternatives I can think of are using NFS and using NBD.
>>> Maybe there's some kind of loopback device I could use on the disk image
>>> to access it from the host.
>> 
>> I've never tried it on my own, but there is also virtio-9p:
>> 
>> http://wiki.qemu.org/Documentation/9psetup
>> 
>> Maybe that's what you need?
>> 
>> Thomas
> At first I saw Plan 9 and figured it was irrelevant to linux, but the
> example seems to be Linux.  So I'm puzzled.
> Ross
> 
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: How to share filesystem

[shendl1978]

9p  is a protocol that is created by plan 9 operation  system.
linux can use virtio-9p.

发自我的 iPhone

> 在 2013年9月25日，3:03，shendl1978@gmail.com 写道：
> 
> You。can use. Virtio-9p.  In. Linux.
> 
> 发自我的 iPhone
> 
>>> 在 2013年9月25日，0:37，Ross Boylan <ross@biostat.ucsf.edu> 写道：
>>> 
>>> On Tue, 2013-09-24 at 12:24 +0200, Thomas Huth wrote:
>>> Am Tue, 24 Sep 2013 01:38:39 -0700
>>> schrieb Ross Boylan <ross@biostat.ucsf.edu>:
>>> 
>>>> I would like to have access to the same file system from the host and
>>>> the guest.  Can anyone recommend the best way to do this, considering
>>>> ease of use, safety (concurrent access from guest and host does not
>>>> corrupt) and performance?
>>> [...]
>>>> Among the alternatives I can think of are using NFS and using NBD.
>>>> Maybe there's some kind of loopback device I could use on the disk image
>>>> to access it from the host.
>>> 
>>> I've never tried it on my own, but there is also virtio-9p:
>>> 
>>> http://wiki.qemu.org/Documentation/9psetup
>>> 
>>> Maybe that's what you need?
>>> 
>>> Thomas
>> At first I saw Plan 9 and figured it was irrelevant to linux, but the
>> example seems to be Linux.  So I'm puzzled.
>> Ross
>> 
>> --
>> To unsubscribe from this list: send the line "unsubscribe kvm" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: How to share filesystem

[Ross Boylan]

On Wed, 2013-09-25 at 03:06 +0800, shendl1978@gmail.com wrote:
> 9p  is a protocol that is created by plan 9 operation  system.
> linux can use virtio-9p.
> 
> 发自我的 iPhone
Is this the preferred way to go?

At any rate, I don't think I can use it easily because the wiki says it
needs linux 2.6.36.rc4 or newer, and Lenny uses 2.6.26 and backports
only has 2.6.32.

Ross
> 
> > 在 2013年9月25日，3:03，shendl1978@gmail.com 写道：
> > 
> > You。can use. Virtio-9p.  In. Linux.
> > 
> > 发自我的 iPhone
> > 
> >>> 在 2013年9月25日，0:37，Ross Boylan <ross@biostat.ucsf.edu> 写道：
> >>> 
> >>> On Tue, 2013-09-24 at 12:24 +0200, Thomas Huth wrote:
> >>> Am Tue, 24 Sep 2013 01:38:39 -0700
> >>> schrieb Ross Boylan <ross@biostat.ucsf.edu>:
> >>> 
> >>>> I would like to have access to the same file system from the host and
> >>>> the guest.  Can anyone recommend the best way to do this, considering
> >>>> ease of use, safety (concurrent access from guest and host does not
> >>>> corrupt) and performance?
> >>> [...]
> >>>> Among the alternatives I can think of are using NFS and using NBD.
> >>>> Maybe there's some kind of loopback device I could use on the disk image
> >>>> to access it from the host.
> >>> 
> >>> I've never tried it on my own, but there is also virtio-9p:
> >>> 
> >>> http://wiki.qemu.org/Documentation/9psetup
> >>> 
> >>> Maybe that's what you need?
> >>> 
> >>> Thomas
> >> At first I saw Plan 9 and figured it was irrelevant to linux, but the
> >> example seems to be Linux.  So I'm puzzled.
> >> Ross
> >> 
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe kvm" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: How to share filesystem

[Brian Jackson]

On Tuesday, September 24, 2013 3:38:39 AM CDT, Ross Boylan wrote:
> I would like to have access to the same file system from the host and
> the guest.  Can anyone recommend the best way to do this, considering
> ease of use, safety (concurrent access from guest and host does not
> corrupt) and performance?
>
> For example, I would like to restore files from backup using the host,
> but write to filesystems used by the guest.
>
> I have previously used kvm mostly with disks that are based on LVM
> logical volumes, e.g. -hda /dev/turtle/Squeeze00.  Since the LVs are
> virtual disks, I can't just mount them in the host AFAIK.
>
> Among the alternatives I can think of are using NFS and using NBD.
> Maybe there's some kind of loopback device I could use on the disk image
> to access it from the host.


I would suggest NFS/CIFS generally speaking. 9p/virtio is an option, but 
NFS and CIFS are going to be far more stable, tested, and fast.


>
> Host: Debian GNU/Linux wheezy, amd64 architecture, qemu-kvm 1.1.2
> Guest: Debian GNU/Linux lenny i386.
> Host processor is a recent i5 with good virtualization (flaga: fpu vme
> de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush
> dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm
> constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc
> aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3
> cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes
> xsave avx f16c rdrand lahf_lm ida arat epb xsaveopt pln pts dtherm
> tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms)
>
> Thanks.
> Ross Boylan
>
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>