On Thu, 17 Apr 2014 08:14:04 -0500 John-Paul Robinson wrote:
> So in the mean time, are there any common work-arounds?
>
> I'm assuming monitoring imageused/imagesize ratio and if its greater
> than some tolerance create a new image and move file system content over
> is an effective, if crude approach. I'm not clear on how to measure the
> amount of storage an image uses at the RBD level. Probably because I
> don't understand info output:
>
You count the objects and multiply by the object size, 4MB by default and
in your case.
For example:
---
# rbd info rbd-test
rbd image 'rbd-test':
size 200 GB in 51200 objects
order 22 (4096 kB objects)
block_name_prefix: rb.0.1025.2ae8944a
format: 1
# rados -p rbd ls |grep rb.0.1025.2ae8944a|wc -l
43382
---
This test image has been used for countless fio and bonnie++ runs and thus
is nearly using all the space and very much could benefit from a TRIM run.
Normal VM images will creep up to full disk usage (allocation) much slower
of course.
> $ sudo rbd --id nova info somecontainer
> rbd image 'somecontainer':
> size 1024 GB in 262144 objects
> order 22 (4096 kB objects)
> block_name_prefix: rb.0.176f3.238e1f29
> format: 1
>
Hang on a second.
This looks like your using Openstack and nova for VM disks.
Your original mail made it look like you're using just the kernelspace
interface.
I'm not an Openstack expert, after evaluating it last year and finding out
that it doesn't do what I want/need it to do it is on the backburner here.
However I'm pretty sure you can use fstrim from within a VM there provided
that:
1. You use userspace RBD with a proper version of qemu (KVM).
2. Have the disk in question being of type IDE or virtio-scsi (see my
previous reply).
Regards,
Christian
> Are there others?
>
> I assume snapshotting images doesn't help here since RBD still wouldn't
> be able to distinguish what's in use and what's not.
>
> Thoughts?
>
> ~jpr
>
> On 04/17/2014 01:38 AM, Wido den Hollander wrote:
> > On 04/17/2014 02:39 AM, Somnath Roy wrote:
> >> It seems Discard support for kernel rbd is targeted for v80..
> >>
> >> http://tracker.ceph.com/issues/190
> >>
> >
> > True, but it will obviously take time before this hits the upstream
> > kernels and goes into distributions.
> >
> > For RHEL 7 it might be that the krbd module from the Ceph extra repo
> > might work. For Ubuntu it's waiting for newer kernels to be backported
> > to the LTS releases.
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>
--
Christian Balzer Network/Systems Engineer
ch...@gol.com Global OnLine Japan/Fusion Communications
http://www.gol.com/
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