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Posted to users@cloudstack.apache.org by Andrei Mikhailovsky <an...@arhont.com> on 2013/01/30 18:25:16 UTC
Slow snapshots with KVM
Hello guys,
I was wondering if there is a way to speed up the creation of snapshots in CS + KVM? It seems that every time the snapshot is created an entire vm disk image is copied over from primary to secondary storage which could take ages if your images are 100GB+. I remember that taking images in vmware / xenserver takes minutes if not seconds. Does the problem relate to KVM or is it a CloudStack design issue of separating primary and secondary storage?
Many thanks
Andrei
Re: Slow snapshots with KVM
Posted by Andrei Mikhailovsky <an...@arhont.com>.
Many thanks for all your answers. Indeed, the term Snapshot is a bit confusing, perhaps it should be called something else ))). The trouble with the term Snapshot here is that the users will think it's a Snapshot and will start using it left, right and centre without realising that it takes ages to do, especially if many people are doing that simultaneously and it consumes far more disk space compared with the traditional Snapshotting )))
----- Original Message -----
From: "Paul Angus" <pa...@shapeblue.com>
To: cloudstack-users@incubator.apache.org
Sent: Thursday, 31 January, 2013 7:23:00 AM
Subject: RE: Slow snapshots with KVM
These are all valid points, but in the end CloudStack 'snapshots' do not behave in the way people from a virtualisation background are likely to expect them to; You can't just press a button and roll back, you can only create a clone of that VM which will have a different MAC and a new IP address and possibly a new hostname...
I agree it may not be the best backup solution, but IMHO 'a backup' is closer fit for the functionality than a snapshot.
Maybe we should all start calling a it a 'Clone'?
Regards,
Paul Angus
S: +44 20 3603 0540 | M: +447711418784
paul.angus@shapeblue.com
-----Original Message-----
From: Nux! [mailto:nux@li.nux.ro]
Sent: 30 January 2013 23:25
To: cloudstack-users@incubator.apache.org
Subject: Re: Slow snapshots with KVM
On 30.01.2013 22:48, David Nalley wrote:
>
> As long as you realize that these are 'crash consistent' snapshots,
> then yes. I personally dislike using the term 'backup' for snapshots -
> it's certainly not a method I'd use to backup data that was important
> to me.
>
> --David
Crash consistent can be great when you don't have anything else. :-) Plus another advantage of a full snapshot is that there's no I/O cost in maintaing it vs the changes in "master", like it is with the e.g. lvm snapshots. So there are advantages and disadvantages..
--
Sent from the Delta quadrant using Borg technology!
Nux!
www.nux.ro
ShapeBlue provides a range of strategic and technical consulting and implementation services to help IT Service Providers and Enterprises to build a true IaaS compute cloud. ShapeBlue’s expertise, combined with CloudStack technology, allows IT Service Providers and Enterprises to deliver true, utility based, IaaS to the customer or end-user.
________________________________
This email and any attachments to it may be confidential and are intended solely for the use of the individual to whom it is addressed. Any views or opinions expressed are solely those of the author and do not necessarily represent those of Shape Blue Ltd. If you are not the intended recipient of this email, you must neither take any action based upon its contents, nor copy or show it to anyone. Please contact the sender if you believe you have received this email in error. Shape Blue Ltd is a company incorporated in England & Wales.
RE: Slow snapshots with KVM
Posted by Paul Angus <pa...@shapeblue.com>.
These are all valid points, but in the end CloudStack 'snapshots' do not behave in the way people from a virtualisation background are likely to expect them to; You can't just press a button and roll back, you can only create a clone of that VM which will have a different MAC and a new IP address and possibly a new hostname...
I agree it may not be the best backup solution, but IMHO 'a backup' is closer fit for the functionality than a snapshot.
Maybe we should all start calling a it a 'Clone'?
Regards,
Paul Angus
S: +44 20 3603 0540 | M: +447711418784
paul.angus@shapeblue.com
-----Original Message-----
From: Nux! [mailto:nux@li.nux.ro]
Sent: 30 January 2013 23:25
To: cloudstack-users@incubator.apache.org
Subject: Re: Slow snapshots with KVM
On 30.01.2013 22:48, David Nalley wrote:
>
> As long as you realize that these are 'crash consistent' snapshots,
> then yes. I personally dislike using the term 'backup' for snapshots -
> it's certainly not a method I'd use to backup data that was important
> to me.
>
> --David
Crash consistent can be great when you don't have anything else. :-) Plus another advantage of a full snapshot is that there's no I/O cost in maintaing it vs the changes in "master", like it is with the e.g. lvm snapshots. So there are advantages and disadvantages..
--
Sent from the Delta quadrant using Borg technology!
Nux!
www.nux.ro
ShapeBlue provides a range of strategic and technical consulting and implementation services to help IT Service Providers and Enterprises to build a true IaaS compute cloud. ShapeBlue’s expertise, combined with CloudStack technology, allows IT Service Providers and Enterprises to deliver true, utility based, IaaS to the customer or end-user.
________________________________
This email and any attachments to it may be confidential and are intended solely for the use of the individual to whom it is addressed. Any views or opinions expressed are solely those of the author and do not necessarily represent those of Shape Blue Ltd. If you are not the intended recipient of this email, you must neither take any action based upon its contents, nor copy or show it to anyone. Please contact the sender if you believe you have received this email in error. Shape Blue Ltd is a company incorporated in England & Wales.
Re: Slow snapshots with KVM
Posted by Nux! <nu...@li.nux.ro>.
On 30.01.2013 22:48, David Nalley wrote:
>
> As long as you realize that these are 'crash consistent' snapshots,
> then yes. I personally dislike using the term 'backup' for snapshots -
> it's certainly not a method I'd use to backup data that was important
> to me.
>
> --David
Crash consistent can be great when you don't have anything else. :-)
Plus another advantage of a full snapshot is that there's no I/O cost
in maintaing it vs the changes in "master", like it is with the e.g. lvm
snapshots. So there are advantages and disadvantages..
--
Sent from the Delta quadrant using Borg technology!
Nux!
www.nux.ro
Re: Slow snapshots with KVM
Posted by David Nalley <da...@gnsa.us>.
On Wed, Jan 30, 2013 at 5:04 PM, Nux! <nu...@li.nux.ro> wrote:
> On 30.01.2013 21:14, Ahmad Emneina wrote:
>>
>> KVM does a snapshot of the whole disk, as opposed to delta's like
>> xenserver. Which is why your kvm snapshots take ages to copy to secondary
>> storage.
>
>
> Is then safe to assume that a Cloudstack KVM snapshot can be used as a "full
> backup" that can be restored even though there is nothing left of the
> original virtual machine? Doesn't sound so bad from a reliability point of
> view; an incremental/delta snapshot would not be of much case in a disaster
> scenario.
>
As long as you realize that these are 'crash consistent' snapshots,
then yes. I personally dislike using the term 'backup' for snapshots -
it's certainly not a method I'd use to backup data that was important
to me.
--David
Re: Slow snapshots with KVM
Posted by Ahmad Emneina <ae...@gmail.com>.
Restoring a full backup to a point in time is 'easier' with full backups.
It's heavy on storage/networking relating to the operations. Delta's
maintain a reference to their parents so full backups are what you get when
you restore from a specific delta... with the efficiency in
networking/storage as a value add. It would be nice to see delta's in KVM.
On Wed, Jan 30, 2013 at 2:04 PM, Nux! <nu...@li.nux.ro> wrote:
> On 30.01.2013 21:14, Ahmad Emneina wrote:
>
>> KVM does a snapshot of the whole disk, as opposed to delta's like
>> xenserver. Which is why your kvm snapshots take ages to copy to secondary
>> storage.
>>
>
> Is then safe to assume that a Cloudstack KVM snapshot can be used as a
> "full backup" that can be restored even though there is nothing left of the
> original virtual machine? Doesn't sound so bad from a reliability point of
> view; an incremental/delta snapshot would not be of much case in a disaster
> scenario.
>
> --
> Sent from the Delta quadrant using Borg technology!
>
> Nux!
> www.nux.ro
>
Re: Slow snapshots with KVM
Posted by Nux! <nu...@li.nux.ro>.
On 30.01.2013 21:14, Ahmad Emneina wrote:
> KVM does a snapshot of the whole disk, as opposed to delta's like
> xenserver. Which is why your kvm snapshots take ages to copy to
> secondary
> storage.
Is then safe to assume that a Cloudstack KVM snapshot can be used as a
"full backup" that can be restored even though there is nothing left of
the original virtual machine? Doesn't sound so bad from a reliability
point of view; an incremental/delta snapshot would not be of much case
in a disaster scenario.
--
Sent from the Delta quadrant using Borg technology!
Nux!
www.nux.ro
Re: Slow snapshots with KVM
Posted by Ahmad Emneina <ae...@gmail.com>.
KVM does a snapshot of the whole disk, as opposed to delta's like
xenserver. Which is why your kvm snapshots take ages to copy to secondary
storage.
On Wed, Jan 30, 2013 at 12:59 PM, Paul Angus <pa...@shapeblue.com>wrote:
> Hi Andrei,
>
> CloudStack snapshots are currently best thought off as back-ups rather
> than snapshots.
>
> Although CloudStack leverages the hypervisor's native snapshot technology,
> it then copies/movies the hypervisor level snapshot to secondary storage.
> CloudStack doesn't declare the snapshot task finished until the snapshot
> has finished copying to secondary storage which can take a long time
> especially if you've got 100GB+ images.
>
> Given that you can't simply 'roll-back' a VM to its snapshot state, as I
> say, it's best to think of them as backups rather than snapshots.
>
>
> Regards,
>
> Paul Angus
> S: +44 20 3603 0540 | M: +447711418784
> paul.angus@shapeblue.com
>
> -----Original Message-----
> From: Andrei Mikhailovsky [mailto:andrei@arhont.com]
> Sent: 30 January 2013 17:25
> To: cloudstack-users@incubator.apache.org
> Subject: Slow snapshots with KVM
>
> Hello guys,
>
> I was wondering if there is a way to speed up the creation of snapshots in
> CS + KVM? It seems that every time the snapshot is created an entire vm
> disk image is copied over from primary to secondary storage which could
> take ages if your images are 100GB+. I remember that taking images in
> vmware / xenserver takes minutes if not seconds. Does the problem relate to
> KVM or is it a CloudStack design issue of separating primary and secondary
> storage?
>
> Many thanks
>
> Andrei
> ShapeBlue provides a range of strategic and technical consulting and
> implementation services to help IT Service Providers and Enterprises to
> build a true IaaS compute cloud. ShapeBlue’s expertise, combined with
> CloudStack technology, allows IT Service Providers and Enterprises to
> deliver true, utility based, IaaS to the customer or end-user.
>
> ________________________________
>
> This email and any attachments to it may be confidential and are intended
> solely for the use of the individual to whom it is addressed. Any views or
> opinions expressed are solely those of the author and do not necessarily
> represent those of Shape Blue Ltd. If you are not the intended recipient of
> this email, you must neither take any action based upon its contents, nor
> copy or show it to anyone. Please contact the sender if you believe you
> have received this email in error. Shape Blue Ltd is a company incorporated
> in England & Wales.
>
RE: Slow snapshots with KVM
Posted by Paul Angus <pa...@shapeblue.com>.
Hi Andrei,
CloudStack snapshots are currently best thought off as back-ups rather than snapshots.
Although CloudStack leverages the hypervisor's native snapshot technology, it then copies/movies the hypervisor level snapshot to secondary storage. CloudStack doesn't declare the snapshot task finished until the snapshot has finished copying to secondary storage which can take a long time especially if you've got 100GB+ images.
Given that you can't simply 'roll-back' a VM to its snapshot state, as I say, it's best to think of them as backups rather than snapshots.
Regards,
Paul Angus
S: +44 20 3603 0540 | M: +447711418784
paul.angus@shapeblue.com
-----Original Message-----
From: Andrei Mikhailovsky [mailto:andrei@arhont.com]
Sent: 30 January 2013 17:25
To: cloudstack-users@incubator.apache.org
Subject: Slow snapshots with KVM
Hello guys,
I was wondering if there is a way to speed up the creation of snapshots in CS + KVM? It seems that every time the snapshot is created an entire vm disk image is copied over from primary to secondary storage which could take ages if your images are 100GB+. I remember that taking images in vmware / xenserver takes minutes if not seconds. Does the problem relate to KVM or is it a CloudStack design issue of separating primary and secondary storage?
Many thanks
Andrei
ShapeBlue provides a range of strategic and technical consulting and implementation services to help IT Service Providers and Enterprises to build a true IaaS compute cloud. ShapeBlue’s expertise, combined with CloudStack technology, allows IT Service Providers and Enterprises to deliver true, utility based, IaaS to the customer or end-user.
________________________________
This email and any attachments to it may be confidential and are intended solely for the use of the individual to whom it is addressed. Any views or opinions expressed are solely those of the author and do not necessarily represent those of Shape Blue Ltd. If you are not the intended recipient of this email, you must neither take any action based upon its contents, nor copy or show it to anyone. Please contact the sender if you believe you have received this email in error. Shape Blue Ltd is a company incorporated in England & Wales.