Re: Ceph RBD object-map and discard in VM

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



I've created a downstream bug for this same issue.

https://bugzilla.redhat.com/show_bug.cgi?id=1349116

On Wed, Jun 15, 2016 at 6:23 AM, <list@xxxxxxxxxxxxxxx> wrote:
Hello guys,

We are currently testing Ceph Jewel with object-map feature enabled:

rbd image 'disk-22920':
        size 102400 MB in 25600 objects
        order 22 (4096 kB objects)
        block_name_prefix: rbd_data.7cfa2238e1f29
        format: 2
        features: layering, exclusive-lock, object-map, fast-diff, deep-flatten
        flags:

We use this RBD as disk for a kvm virtual machine with virtio-scsi and discard=unmap. We noticed the following paremeters in /sys/block:

# cat /sys/block/sda/queue/discard_*
4096
1073741824
0 <- discard_zeroes_data

While trying to do a mkfs.ext4 on the disk in VM we noticed a low performance with using discard.

mkfs.ext4 -E nodiscard /dev/sda1 - tooks 5 seconds to complete
mkfs.ext4 -E discard /dev/sda1 - tooks around 3 monutes

When disabling the object-map the mkfs with discard tooks just 5 seconds.

Do you have any idea what might cause this issue?

Kernel: 4.2.0-35-generic #40~14.04.1-Ubuntu
Ceph: 10.2.0
Libvirt: 1.3.1
QEMU: 2.5.0

Thanks!

Best regards,
Jonas
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com



--
Brian Andrus
Red Hat, Inc.
Storage Consultant, Global Storage Practice
Mobile +1 (530) 903-8487

_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com

[Index of Archives]     [Information on CEPH]     [Linux Filesystem Development]     [Ceph Development]     [Ceph Large]     [Ceph Dev]     [Linux USB Development]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [xfs]


  Powered by Linux