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

Re: [Xen-devel] Xen disk write slowness in kernel 3.8.x

On 03/04/13 22:36, Felipe Franciosi wrote:
Based on what you said later, your raid stripe size is 128KB. When you plug 
/dev/md3 to your guest, you will be going through blkback/blkfront which only 
support 44KB per request.

This is interesting. The default size for a RAID5/6 via mdadm these days is 512Kb.

So can I ask what is the "task that is going on"?
I mean, what is your workload and how does it look like (in terms of 
reads/writes, (a)sync and size)?

The load is mostly sequential writes. Samba + NFS shares mainly. Files are usually 300Mb -> 10Gb. Its mostly writes, with occasional reads. Interestingly, I get 220Mb/sec+ reads - but only ~50Mb/sec writes via the DomU.

Steven Haigh

Email: netwiz@xxxxxxxxx
Web: https://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897
Fax: (03) 8338 0299

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.