Re: KVM qcow2 perfomance

[Ivan Kudryavtsev]

Hi. No offence, but as topic author wrote, he has 30MB/s. Just kept it in
mind when wrote about 100.

7 авг. 2017 г. 3:01 пользователь "Eric Green" 
написал:

>
> > On Aug 5, 2017, at 21:03, Ivan Kudryavtsev 
> wrote:
> >
> > Hi, I think Eric's comments are too tough. E.g. I have 11xSSD 1TB with
> > linux soft raid 5 and Ext4 and it works like a charm without special
> > tunning.
> >
> > Qcow2 also not so bad. LVM2 does it better of course (if not being
> > snapshotted). Our users have different workloads and nobody claims disk
> > performance is a problem. Read/write 100 MB/sec over 10G connection is
> not
> > a problem at all for the setup specified above.
>
> 100 MB/sec is the speed of a single vintage 2010 5200 RPM SATA-2 drive.
> For many people, that is not a problem. For some, it is. For example, I
> have a 12x-SSD RAID10 for a database. This RAID10 is on a SAS2 bus with 4
> channels thus capable of 2.4 gigaBYTES per second raw throughput. Yes, I
> have validated that the SAS2 bus is the limit on throughput for my SSD
> array. If I provided a qcow2 volume to the database instance that only
> managed 100MB/sec, my database people would howl.
>
> I have many virtual machines that run quite happily with thin qcow2
> volumes on 12-disk RAID6 XFS datastores (spinning storage) with no problem,
> because they don't care about disk throughput, they are there to process
> data, or provide services like DNS or a Wiki knowledge base, or otherwise
> do things that aren't particularly time-critical in our environment. So
> it's all about your customer and his needs. For maximum throughput, qcow2
> on a ext4 soft RAID capable of doing 100Mb/sec is very... 2010 spinning
> storage... and people who need more than that, like database people, will
> be extremely dissatisfied.
>
> Thus my suggestions of ways to improve performance via providing a custom
> disk offering for those cases where disk performance and specifically write
> performance is a problem -- switching to 'sparse' rather than 'thin' as the
> provisioning mechanism (which greatly speeds writes since now only the
> filesystem block allocation mechanisms get invoked, rather than qcow2's
> block allocation mechanisms, and qcow2 now only has a single allocation
> zone which greatly speeds its own lookups), using a different underlying
> filesystem that has proven to have more consistent performance (xfs isn't
> much faster than ext4 under most scenarios but doesn't have the lengthy
> dropouts in performance that come with lots of writes on ext4), and
> possibly flipping on async caching in the disk offering if data integrity
> isn't a problem (for example, for an Elasticsearch instance, the data is
> all replicated across multiple nodes on multiple datastores anyhow, so if I
> lose an Elasticsearch node's data so what? I just destroy that instance and
> create a new one to join to the cluster!). And of course there's always the
> option of simply avoiding qcow2 altogether and providing the data via iSCSI
> or NFS directly to the instance, which may be what you need to do for
> something like a database that has some very specific performance and
> throughput requirements.
>
>
>

Re: KVM qcow2 perfomance

[Eric Green]

> On Aug 5, 2017, at 21:03, Ivan Kudryavtsev  wrote:
> 
> Hi, I think Eric's comments are too tough. E.g. I have 11xSSD 1TB with
> linux soft raid 5 and Ext4 and it works like a charm without special
> tunning.
> 
> Qcow2 also not so bad. LVM2 does it better of course (if not being
> snapshotted). Our users have different workloads and nobody claims disk
> performance is a problem. Read/write 100 MB/sec over 10G connection is not
> a problem at all for the setup specified above.

100 MB/sec is the speed of a single vintage 2010 5200 RPM SATA-2 drive. For 
many people, that is not a problem. For some, it is. For example, I have a 
12x-SSD RAID10 for a database. This RAID10 is on a SAS2 bus with 4 channels 
thus capable of 2.4 gigaBYTES per second raw throughput. Yes, I have validated 
that the SAS2 bus is the limit on throughput for my SSD array. If I provided a 
qcow2 volume to the database instance that only managed 100MB/sec, my database 
people would howl.

I have many virtual machines that run quite happily with thin qcow2 volumes on 
12-disk RAID6 XFS datastores (spinning storage) with no problem, because they 
don't care about disk throughput, they are there to process data, or provide 
services like DNS or a Wiki knowledge base, or otherwise do things that aren't 
particularly time-critical in our environment. So it's all about your customer 
and his needs. For maximum throughput, qcow2 on a ext4 soft RAID capable of 
doing 100Mb/sec is very... 2010 spinning storage... and people who need more 
than that, like database people, will be extremely dissatisfied. 

Thus my suggestions of ways to improve performance via providing a custom disk 
offering for those cases where disk performance and specifically write 
performance is a problem -- switching to 'sparse' rather than 'thin' as the 
provisioning mechanism (which greatly speeds writes since now only the 
filesystem block allocation mechanisms get invoked, rather than qcow2's block 
allocation mechanisms, and qcow2 now only has a single allocation zone which 
greatly speeds its own lookups), using a different underlying filesystem that 
has proven to have more consistent performance (xfs isn't much faster than ext4 
under most scenarios but doesn't have the lengthy dropouts in performance that 
come with lots of writes on ext4), and possibly flipping on async caching in 
the disk offering if data integrity isn't a problem (for example, for an 
Elasticsearch instance, the data is all replicated across multiple nodes on 
multiple datastores anyhow, so if I lose an Elasticsearch node's data so what? 
I just destroy that instance and create a new one to join to the cluster!). And 
of course there's always the option of simply avoiding qcow2 altogether and 
providing the data via iSCSI or NFS directly to the instance, which may be what 
you need to do for something like a database that has some very specific 
performance and throughput requirements.

Re: KVM qcow2 perfomance

[Ivan Kudryavtsev]

Hi, I think Eric's comments are too tough. E.g. I have 11xSSD 1TB with
linux soft raid 5 and Ext4 and it works like a charm without special
tunning.

Qcow2 also not so bad. LVM2 does it better of course (if not being
snapshotted). Our users have different workloads and nobody claims disk
performance is a problem. Read/write 100 MB/sec over 10G connection is not
a problem at all for the setup specified above.

The most cases when write degradation happens for my case is cpu single
core bottleneck for mdadm write operations.

But, frankly speaking I'm mostly IOPS guy rather than bandwidth guy.

Have a great day.

6 авг. 2017 г. 0:59 пользователь "Eric Green" 
написал:

> qcow2 performance has been historically bad regardless of the underlying
> storage (it is an absolutely terrible storage format), which is why most
> OpenStack Kilo and later installations instead usually use managed LVM and
> present LVM volumes as iSCSI volumes to QEMU, because using raw LVM volumes
> directly works quite a bit better (especially since you can do "thick"
> volumes, which get you the best performance, without having to zero out a
> large file on disk). But Cloudstack doesn't use that paradigm. Still, you
> can get much better performance with qcow2 regardless:
>
> 1) Create a disk offering that creates 'sparse' qcow2 volumes (the
> 'sparse' provisioning type). Otherwise every write is actually multiple
> writes -- one to extend the previous qcow2 file, one to update the inode
> with the new file size, and one to update the qcow2 file's own notion of
> how long it is and what all of its sections are, and one to write the
> actual data. And these are all *small* random writes, which SSD's have
> historically been bad at due to write zones. Note that if you look at a
> freshly provisioned 'sparse' file in the actual data store, it might look
> like it's taking up 2tb of space, but it's actually taking up only a few
> blocks.
>
> 2) In that disk offering, if you care more about performance than about
> reliability, set the caching mode to 'writeback'. (The default is 'none').
> This will result in larger writes to the SSD, which it'll do at higher
> rates of speeds than small writes. The downside is that your hardware and
> OS better be *ultra* reliable with battery backup and clean shutdown in
> case of power failure and etc., or the data in question is toast if
> something crashes or the power goes out. So consider how important the data
> is before selecting this option.
>
> 3) If you have a lot of time and want to pre-provision your disks in full,
> in that disk offering set the provisioning type to 'fat'. This will
> pre-zero a qcow2 file of the full size that you selected. Be aware that
> Cloudstack does this zeroing of a volume commissioned with this offering
> type *when you attach it to a virtual machine*, not when you create it. So
> attach it to a "trash" virtual machine first before you attach it to your
> "real" virtual machine, unless you want a lot of downtime waiting for it to
> zero. But assuming you have a host filesystem that properly allocates files
> on a per-extent basis, and the extents match up with the underlying SSD
> write block size well, you should be able to get within 5% of hardware
> performance with 'fat' qcow2. (With 'thin' you can still come within 10% of
> that, which is why 'thin' might be the best for most workloads that require
> performance, and 'thin' doesn't waste space on blocks that have never been
> written and doesn't tie up your storage system for hours zeroing out a 2tb
> qcow2 file, so consider that if thinking 'fat').
>
> 4) USE XFS AS THE HOST FILESYSTEM FOR THE DATASTORE. ext4 will be
> *terrible*. I'm not sure what causes the bad will between ext4 on the
> storage host and qcow2, but I've seen it multiple times in my own testing
> of raw libvirt (no CloudStack). As for btrfs, btrfs will be terrible with
> regular 'thin' qcow2. There is an interaction between its write cycles and
> qcow2's write patterns that, as with ext4, causes very slow performance. I
> have not tested sparse qcow2 with btrfs because I don't trust btrfs, it has
> many design decisions reminiscent of ReiserFS, which ate many Linux
> filesystems back during the day. I have not tested ZFS. The ZFS on Linux
> implementation generally has good but not great performance, it was written
> for reliability, not performance, so it seemed a waste of my time to test
> it. I may do that this weekend however just to see. I inherited a PCIe M2.e
> SSD, you see, and want to see what having that as the write cache device
> will do for performance
>
> 5) For the guest filesystem it really depends on your workload and the
> guest OS. I love ext4 for reliability inside a virtual machine, because you
> can't just lose an entire ext4 filesystem (it's based on ext2/ext3, which
> in turn were created when hardware was much less reliable than today and
> thus has a lot of features to keep you from 

Re: KVM qcow2 perfomance

[Rubens Malheiro]

Wow great explanation! Thank you Eric!
On Sat, 5 Aug 2017 at 14:59 Eric Green  wrote:

> qcow2 performance has been historically bad regardless of the underlying
> storage (it is an absolutely terrible storage format), which is why most
> OpenStack Kilo and later installations instead usually use managed LVM and
> present LVM volumes as iSCSI volumes to QEMU, because using raw LVM volumes
> directly works quite a bit better (especially since you can do "thick"
> volumes, which get you the best performance, without having to zero out a
> large file on disk). But Cloudstack doesn't use that paradigm. Still, you
> can get much better performance with qcow2 regardless:
>
> 1) Create a disk offering that creates 'sparse' qcow2 volumes (the
> 'sparse' provisioning type). Otherwise every write is actually multiple
> writes -- one to extend the previous qcow2 file, one to update the inode
> with the new file size, and one to update the qcow2 file's own notion of
> how long it is and what all of its sections are, and one to write the
> actual data. And these are all *small* random writes, which SSD's have
> historically been bad at due to write zones. Note that if you look at a
> freshly provisioned 'sparse' file in the actual data store, it might look
> like it's taking up 2tb of space, but it's actually taking up only a few
> blocks.
>
> 2) In that disk offering, if you care more about performance than about
> reliability, set the caching mode to 'writeback'. (The default is 'none').
> This will result in larger writes to the SSD, which it'll do at higher
> rates of speeds than small writes. The downside is that your hardware and
> OS better be *ultra* reliable with battery backup and clean shutdown in
> case of power failure and etc., or the data in question is toast if
> something crashes or the power goes out. So consider how important the data
> is before selecting this option.
>
> 3) If you have a lot of time and want to pre-provision your disks in full,
> in that disk offering set the provisioning type to 'fat'. This will
> pre-zero a qcow2 file of the full size that you selected. Be aware that
> Cloudstack does this zeroing of a volume commissioned with this offering
> type *when you attach it to a virtual machine*, not when you create it. So
> attach it to a "trash" virtual machine first before you attach it to your
> "real" virtual machine, unless you want a lot of downtime waiting for it to
> zero. But assuming you have a host filesystem that properly allocates files
> on a per-extent basis, and the extents match up with the underlying SSD
> write block size well, you should be able to get within 5% of hardware
> performance with 'fat' qcow2. (With 'thin' you can still come within 10% of
> that, which is why 'thin' might be the best for most workloads that require
> performance, and 'thin' doesn't waste space on blocks that have never been
> written and doesn't tie up your storage system for hours zeroing out a 2tb
> qcow2 file, so consider that if thinking 'fat').
>
> 4) USE XFS AS THE HOST FILESYSTEM FOR THE DATASTORE. ext4 will be
> *terrible*. I'm not sure what causes the bad will between ext4 on the
> storage host and qcow2, but I've seen it multiple times in my own testing
> of raw libvirt (no CloudStack). As for btrfs, btrfs will be terrible with
> regular 'thin' qcow2. There is an interaction between its write cycles and
> qcow2's write patterns that, as with ext4, causes very slow performance. I
> have not tested sparse qcow2 with btrfs because I don't trust btrfs, it has
> many design decisions reminiscent of ReiserFS, which ate many Linux
> filesystems back during the day. I have not tested ZFS. The ZFS on Linux
> implementation generally has good but not great performance, it was written
> for reliability, not performance, so it seemed a waste of my time to test
> it. I may do that this weekend however just to see. I inherited a PCIe M2.e
> SSD, you see, and want to see what having that as the write cache device
> will do for performance
>
> 5) For the guest filesystem it really depends on your workload and the
> guest OS. I love ext4 for reliability inside a virtual machine, because you
> can't just lose an entire ext4 filesystem (it's based on ext2/ext3, which
> in turn were created when hardware was much less reliable than today and
> thus has a lot of features to keep you from losing an entire filesystem
> just because a few blocks went AWOL), but it's not a very fast filesystem.
> Xfs in my testing has the best performance for virtually all workloads.
> Generally, I use ext4 for root volumes, and make decisions for data volumes
> based upon how important the performance versus reliability equation works
> out for me. I have a lot of ext4 filesystems hanging around for data that
> basically sits there in place without many writes but which I don't want to
> lose.
>
> For best performance of all, manage this SSD storage *outside* of
> Cloudstack as a bunch 

Re: KVM qcow2 perfomance

[Eric Green]

qcow2 performance has been historically bad regardless of the underlying 
storage (it is an absolutely terrible storage format), which is why most 
OpenStack Kilo and later installations instead usually use managed LVM and 
present LVM volumes as iSCSI volumes to QEMU, because using raw LVM volumes 
directly works quite a bit better (especially since you can do "thick" volumes, 
which get you the best performance, without having to zero out a large file on 
disk). But Cloudstack doesn't use that paradigm. Still, you can get much better 
performance with qcow2 regardless:

1) Create a disk offering that creates 'sparse' qcow2 volumes (the 'sparse' 
provisioning type). Otherwise every write is actually multiple writes -- one to 
extend the previous qcow2 file, one to update the inode with the new file size, 
and one to update the qcow2 file's own notion of how long it is and what all of 
its sections are, and one to write the actual data. And these are all *small* 
random writes, which SSD's have historically been bad at due to write zones. 
Note that if you look at a freshly provisioned 'sparse' file in the actual data 
store, it might look like it's taking up 2tb of space, but it's actually taking 
up only a few blocks. 

2) In that disk offering, if you care more about performance than about 
reliability, set the caching mode to 'writeback'. (The default is 'none'). This 
will result in larger writes to the SSD, which it'll do at higher rates of 
speeds than small writes. The downside is that your hardware and OS better be 
*ultra* reliable with battery backup and clean shutdown in case of power 
failure and etc., or the data in question is toast if something crashes or the 
power goes out. So consider how important the data is before selecting this 
option.

3) If you have a lot of time and want to pre-provision your disks in full, in 
that disk offering set the provisioning type to 'fat'. This will pre-zero a 
qcow2 file of the full size that you selected. Be aware that Cloudstack does 
this zeroing of a volume commissioned with this offering type *when you attach 
it to a virtual machine*, not when you create it. So attach it to a "trash" 
virtual machine first before you attach it to your "real" virtual machine, 
unless you want a lot of downtime waiting for it to zero. But assuming you have 
a host filesystem that properly allocates files on a per-extent basis, and the 
extents match up with the underlying SSD write block size well, you should be 
able to get within 5% of hardware performance with 'fat' qcow2. (With 'thin' 
you can still come within 10% of that, which is why 'thin' might be the best 
for most workloads that require performance, and 'thin' doesn't waste space on 
blocks that have never been written and doesn't tie up your storage system for 
hours zeroing out a 2tb qcow2 file, so consider that if thinking 'fat'). 

4) USE XFS AS THE HOST FILESYSTEM FOR THE DATASTORE. ext4 will be *terrible*. 
I'm not sure what causes the bad will between ext4 on the storage host and 
qcow2, but I've seen it multiple times in my own testing of raw libvirt (no 
CloudStack). As for btrfs, btrfs will be terrible with regular 'thin' qcow2. 
There is an interaction between its write cycles and qcow2's write patterns 
that, as with ext4, causes very slow performance. I have not tested sparse 
qcow2 with btrfs because I don't trust btrfs, it has many design decisions 
reminiscent of ReiserFS, which ate many Linux filesystems back during the day. 
I have not tested ZFS. The ZFS on Linux implementation generally has good but 
not great performance, it was written for reliability, not performance, so it 
seemed a waste of my time to test it. I may do that this weekend however just 
to see. I inherited a PCIe M2.e SSD, you see, and want to see what having that 
as the write cache device will do for performance

5) For the guest filesystem it really depends on your workload and the guest 
OS. I love ext4 for reliability inside a virtual machine, because you can't 
just lose an entire ext4 filesystem (it's based on ext2/ext3, which in turn 
were created when hardware was much less reliable than today and thus has a lot 
of features to keep you from losing an entire filesystem just because a few 
blocks went AWOL), but it's not a very fast filesystem. Xfs in my testing has 
the best performance for virtually all workloads. Generally, I use ext4 for 
root volumes, and make decisions for data volumes based upon how important the 
performance versus reliability equation works out for me. I have a lot of ext4 
filesystems hanging around for data that basically sits there in place without 
many writes but which I don't want to lose.

For best performance of all, manage this SSD storage *outside* of Cloudstack as 
a bunch of LVM volumes which are exported to virtual machine guests via LIO 
(iSCSI). Even 'sparse' LVM volumes perform better than qcow2 'thin' volumes. If 
you choose to do that, there's some LIO settings 

Re: KVM qcow2 perfomance

[Rubens Malheiro]

Rodrigo what's a version and system nfs server? Network performance between
host pod and storage it's ok?
On Sat, 5 Aug 2017 at 14:03 Ivan Kudryavtsev 
wrote:

> Qcow2 does lazy allocation. Try to write big file inside VM with dd (say
> 10GB), erase it and try again. May be lazy allocation works bad for your
> raid5e.
>
> 5 авг. 2017 г. 23:29 пользователь "Rodrigo Baldasso" <
> rodr...@loophost.com.br> написал:
>
> > Yes.. mounting an lvm volume inside the host works great, ~500Mb/s write
> > speed.. inside the guest i'm using ext4 but the speed is aroung 30mb/s.
> >
> > - - - - - - - - - - - - - - - - - - -
> >
> > Rodrigo Baldasso - LHOST
> >
> > (51) 9 8419-9861
> > - - - - - - - - - - - - - - - - - - -
> > On 05/08/2017 13:26:00, Ivan Kudryavtsev 
> wrote:
> > Rodrigo, is your fio testing shows great results? What filesystem you are
> > using? KVM is known to work very bad over BTRFS.
> >
> > 5 авг. 2017 г. 23:16 пользователь "Rodrigo Baldasso"
> > rodr...@loophost.com.br> написал:
> >
> > Hi Ivan,
> >
> > In fact i'm testing using local storage.. but on NFS I was getting
> similar
> > results also.
> >
> > Thanks!
> >
> > - - - - - - - - - - - - - - - - - - -
> >
> > Rodrigo Baldasso - LHOST
> >
> > (51) 9 8419-9861
> > - - - - - - - - - - - - - - - - - - -
> > On 05/08/2017 13:03:24, Ivan Kudryavtsev wrote:
> > Hi, Rodrigo. It looks strange. Check your NFSconfiguration and network
> > errors, loss. It should work great.
> >
> > 5 авг. 2017 г. 22:22 пользователь "Rodrigo Baldasso"
> > rodr...@loophost.com.br> написал:
> >
> > Hi everyone,
> >
> > I'm having trouble to archive a good I/O rate using cloudstack qcow2 with
> > any type of caching (or even disabled).
> >
> > We have some RAID-5e SSD arrays which give us a very good rates directly
> on
> > the node/host, but on the guest the speed is terrible.
> >
> > Does anyone knows a solution/workaround for this? I never used qcow (only
> > raw+lvm) so I don't know much to do to solve this.
> >
> > Thanks!
> >
>

Re: KVM qcow2 perfomance

[Ivan Kudryavtsev]

Qcow2 does lazy allocation. Try to write big file inside VM with dd (say
10GB), erase it and try again. May be lazy allocation works bad for your
raid5e.

5 авг. 2017 г. 23:29 пользователь "Rodrigo Baldasso" <
rodr...@loophost.com.br> написал:

> Yes.. mounting an lvm volume inside the host works great, ~500Mb/s write
> speed.. inside the guest i'm using ext4 but the speed is aroung 30mb/s.
>
> - - - - - - - - - - - - - - - - - - -
>
> Rodrigo Baldasso - LHOST
>
> (51) 9 8419-9861
> - - - - - - - - - - - - - - - - - - -
> On 05/08/2017 13:26:00, Ivan Kudryavtsev  wrote:
> Rodrigo, is your fio testing shows great results? What filesystem you are
> using? KVM is known to work very bad over BTRFS.
>
> 5 авг. 2017 г. 23:16 пользователь "Rodrigo Baldasso"
> rodr...@loophost.com.br> написал:
>
> Hi Ivan,
>
> In fact i'm testing using local storage.. but on NFS I was getting similar
> results also.
>
> Thanks!
>
> - - - - - - - - - - - - - - - - - - -
>
> Rodrigo Baldasso - LHOST
>
> (51) 9 8419-9861
> - - - - - - - - - - - - - - - - - - -
> On 05/08/2017 13:03:24, Ivan Kudryavtsev wrote:
> Hi, Rodrigo. It looks strange. Check your NFSconfiguration and network
> errors, loss. It should work great.
>
> 5 авг. 2017 г. 22:22 пользователь "Rodrigo Baldasso"
> rodr...@loophost.com.br> написал:
>
> Hi everyone,
>
> I'm having trouble to archive a good I/O rate using cloudstack qcow2 with
> any type of caching (or even disabled).
>
> We have some RAID-5e SSD arrays which give us a very good rates directly on
> the node/host, but on the guest the speed is terrible.
>
> Does anyone knows a solution/workaround for this? I never used qcow (only
> raw+lvm) so I don't know much to do to solve this.
>
> Thanks!
>

Re: KVM qcow2 perfomance

[Rodrigo Baldasso]

Yes.. mounting an lvm volume inside the host works great, ~500Mb/s write 
speed.. inside the guest i'm using ext4 but the speed is aroung 30mb/s.

- - - - - - - - - - - - - - - - - - -

Rodrigo Baldasso - LHOST

(51) 9 8419-9861
- - - - - - - - - - - - - - - - - - -
On 05/08/2017 13:26:00, Ivan Kudryavtsev  wrote:
Rodrigo, is your fio testing shows great results? What filesystem you are
using? KVM is known to work very bad over BTRFS.

5 авг. 2017 г. 23:16 пользователь "Rodrigo Baldasso"
rodr...@loophost.com.br> написал:

Hi Ivan,

In fact i'm testing using local storage.. but on NFS I was getting similar
results also.

Thanks!

- - - - - - - - - - - - - - - - - - -

Rodrigo Baldasso - LHOST

(51) 9 8419-9861
- - - - - - - - - - - - - - - - - - -
On 05/08/2017 13:03:24, Ivan Kudryavtsev wrote:
Hi, Rodrigo. It looks strange. Check your NFSconfiguration and network
errors, loss. It should work great.

5 авг. 2017 г. 22:22 пользователь "Rodrigo Baldasso"
rodr...@loophost.com.br> написал:

Hi everyone,

I'm having trouble to archive a good I/O rate using cloudstack qcow2 with
any type of caching (or even disabled).

We have some RAID-5e SSD arrays which give us a very good rates directly on
the node/host, but on the guest the speed is terrible.

Does anyone knows a solution/workaround for this? I never used qcow (only
raw+lvm) so I don't know much to do to solve this.

Thanks!

Re: KVM qcow2 perfomance

[Ivan Kudryavtsev]

Rodrigo, is your fio testing shows great results? What filesystem you are
using? KVM is known to work very bad over BTRFS.

5 авг. 2017 г. 23:16 пользователь "Rodrigo Baldasso" <
rodr...@loophost.com.br> написал:

Hi Ivan,

In fact i'm testing using local storage.. but on NFS I was getting similar
results also.

Thanks!

- - - - - - - - - - - - - - - - - - -

Rodrigo Baldasso - LHOST

(51) 9 8419-9861
- - - - - - - - - - - - - - - - - - -
On 05/08/2017 13:03:24, Ivan Kudryavtsev  wrote:
Hi, Rodrigo. It looks strange. Check your NFSconfiguration and network
errors, loss. It should work great.

5 авг. 2017 г. 22:22 пользователь "Rodrigo Baldasso"
rodr...@loophost.com.br> написал:

Hi everyone,

I'm having trouble to archive a good I/O rate using cloudstack qcow2 with
any type of caching (or even disabled).

We have some RAID-5e SSD arrays which give us a very good rates directly on
the node/host, but on the guest the speed is terrible.

Does anyone knows a solution/workaround for this? I never used qcow (only
raw+lvm) so I don't know much to do to solve this.

Thanks!

Re: KVM qcow2 perfomance

[Rodrigo Baldasso]

Hi Ivan,

In fact i'm testing using local storage.. but on NFS I was getting similar 
results also.

Thanks!

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Rodrigo Baldasso - LHOST

(51) 9 8419-9861
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On 05/08/2017 13:03:24, Ivan Kudryavtsev  wrote:
Hi, Rodrigo. It looks strange. Check your NFSconfiguration and network
errors, loss. It should work great.

5 авг. 2017 г. 22:22 пользователь "Rodrigo Baldasso"
rodr...@loophost.com.br> написал:

Hi everyone,

I'm having trouble to archive a good I/O rate using cloudstack qcow2 with
any type of caching (or even disabled).

We have some RAID-5e SSD arrays which give us a very good rates directly on
the node/host, but on the guest the speed is terrible.

Does anyone knows a solution/workaround for this? I never used qcow (only
raw+lvm) so I don't know much to do to solve this.

Thanks!

Re: KVM qcow2 perfomance

[Ivan Kudryavtsev]

Hi, Rodrigo. It looks strange. Check your NFSconfiguration and network
errors, loss. It should work great.

5 авг. 2017 г. 22:22 пользователь "Rodrigo Baldasso" <
rodr...@loophost.com.br> написал:

Hi everyone,

I'm having trouble to archive a good I/O rate using cloudstack qcow2 with
any type of caching (or even disabled).

We have some RAID-5e SSD arrays which give us a very good rates directly on
the node/host, but on the guest the speed is terrible.

Does anyone knows a solution/workaround for this? I never used qcow (only
raw+lvm) so I don't know much to do to solve this.

Thanks!