Hi Jason,
Thank you for your advice.
The no discard option works gread.It now takes 5min to format 5t rbd image in 
xfs and only seconds to format in ext4.
Is there any drawback to format rbd image with no discard option?
Thanks


2017-10-31 


lin.yunfan



发件人:Jason Dillaman <jdill...@redhat.com>
发送时间:2017-10-30 03:07
主题:Re: [ceph-users] mkfs rbd image is very slow
收件人:"shadow_lin"<shadow_...@163.com>
抄送:"ceph-users"<ceph-users@lists.ceph.com>

Try running "mkfs.xfs -K" which disables discarding to see if that 
improves the mkfs speed. The librbd-based implementation encountered a 
similar issue before when certain OSs sent very small discard extents 
for very large disks. 

On Sun, Oct 29, 2017 at 10:16 AM, shadow_lin <shadow_...@163.com> wrote: 
> Hi all, 
> I am testing ec pool backed rbd image performace and found that it takes a 
> very long time to format the rbd image by mkfs. 
> I created a 5TB image and mounted it on the client(ubuntu 16.04 with 4.12 
> kernel) and use mkfs.ext4 and mkfs.xfs to format it. 
> It takes hours to finish the format and the load on some osds are high and I 
> can get slow request warning from time to time. 
> 
> What is a reasonable time to format a 5TB rbd image?What should I do to 
> improve it? 
> Thanks 
> 
> 2017-10-29 
> ________________________________ 
> Frank 
> 
> _______________________________________________ 
> ceph-users mailing list 
> ceph-users@lists.ceph.com 
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com 
> 



--  
Jason 
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