Has anyone ever tried the ''ram'' driver with blktap for block
devices?
It''s mentioned here:
http://wiki.xensource.com/xenwiki/blktap
Fast shareable RAM disk between VMs (requires some form of
cluster-based filesystem support e.g. OCFS2 in the guest kernel)
and poking around the source, in tools/blktap there is a README
(almost identical to the above web page) and the drivers themselves.
I''ve been trying to get it to work on CentOS 5.2 to no avail.
Specifically:
block-attach domain ''tap:ram:/path/to/file'' hdb w
..makes something appear in the output of block-list, but the domU
doesn''t react at all. (nothing in dmesg, /dev/dhb is not found
etc...) Sadly, this is exactly the same thing that happens if you
specify a bogus tap driver, (EG tap:wibble:/path/to/file).
I''ve tried tap:aio and tap:sync and they both work.
Thanks!
-Dylan
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users
On Fri, Jan 9, 2009 at 5:42 PM, Dylan Martin <dmartin@sccd.ctc.edu> wrote:> Has anyone ever tried the ''ram'' driver with blktap for block devices? > It''s mentioned here: > > http://wiki.xensource.com/xenwiki/blktap > > Fast shareable RAM disk between VMs (requires some form of > cluster-based filesystem support e.g. OCFS2 in the guest kernel) > > and poking around the source, in tools/blktap there is a README > (almost identical to the above web page) and the drivers themselves. > > I''ve been trying to get it to work on CentOS 5.2 to no avail. Specifically: > > block-attach domain ''tap:ram:/path/to/file'' hdb w > > ..makes something appear in the output of block-list, but the domU > doesn''t react at all. (nothing in dmesg, /dev/dhb is not found > etc...) Sadly, this is exactly the same thing that happens if you > specify a bogus tap driver, (EG tap:wibble:/path/to/file). > > I''ve tried tap:aio and tap:sync and they both work. >I haven''t tried it personally. There has been very little development on it. see: http://lxr.mstier.de/Xen/source/xen_3.2.1/tools/blktap/drivers/block_ram.c?v=3.2.1 http://xen.markmail.org/search/?q=block_ram.c Maybe some hints in the code and/or changes since the CentOS Xen version. Cheers, Todd -- Todd Deshane http://todddeshane.net http://runningxen.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> On Fri, Jan 9, 2009 at 5:42 PM, Dylan Martin <dmartin@sccd.ctc.edu> > wrote: >> Has anyone ever tried the ''ram'' driver with blktap for block devices? >> It''s mentioned here: >> >> http://wiki.xensource.com/xenwiki/blktap >> >> Fast shareable RAM disk between VMs (requires some form of >> cluster-based filesystem support e.g. OCFS2 in the guest kernel) >> >> and poking around the source, in tools/blktap there is a README >> (almost identical to the above web page) and the drivers themselves. >> >> I''ve been trying to get it to work on CentOS 5.2 to no avail. >> Specifically: >> >> block-attach domain ''tap:ram:/path/to/file'' hdb w >> >> ..makes something appear in the output of block-list, but the domU >> doesn''t react at all. (nothing in dmesg, /dev/dhb is not found >> etc...) Sadly, this is exactly the same thing that happens if you >> specify a bogus tap driver, (EG tap:wibble:/path/to/file). >> >> I''ve tried tap:aio and tap:sync and they both work. >> > > I haven''t tried it personally. > > There has been very little development on it. > > see: > http://lxr.mstier.de/Xen/source/xen_3.2.1/tools/blktap/drivers/block_ram.c?v=3.2.1 > http://xen.markmail.org/search/?q=block_ram.c > > Maybe some hints in the code and/or changes since the CentOS Xen > version. > > Cheers, > Todd >I haven''t tested the driver myself, I''ve only copied the descriptions from the README. This line might help in block_ram.c:207 DPRINTF("Reading %llu bytes.......",(long long unsigned)s->size << SECTOR_SHIFT); see if that line appears in your /var/log/messages ..Tim _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users