Re: [Xen-devel] [PATCH] Remus: support both tap and tap2 style disk specs

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Shriram Rajagopalan writes ("Re: [Xen-devel] [PATCH] Remus: support both tap 
and tap2 style disk specs"):
> On Thu, Feb 17, 2011 at 11:04 AM, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> 
> wrote:
> > Shriram Rajagopalan writes ("[Xen-devel] [PATCH] Remus: support both tap 
> > and tap2 style disk specs"):
> >> -        if not disk.uname.startswith('tap:remus:') and not 
> >> disk.uname.startswith('tap:tapdisk:remus:'):
> >> +        disktype = re.match("tap2?:.*(remus.*)\|", disk.uname)
> >> +        if disktype == None:
> >
> > This seems quite a striking change.  What is the tap2 remus syntax
> > like ?
> >
> There is no change in remus syntax.
> remus part of the disk spec just requires "remus:BackupHost:Port|" to
> immediately follow major driver name. so,
> 
>  disk= tap2:remus:BackupHost:Port|aio:volname ...

Your regexp would match
  tap2:aio:file:/path/containing/remus/and/with/a/pipe/symbol|

> the problem is with the initial prefix "tap2:" string.
> Which could be tap: or tap2: or tap:tapdisk or tap2:tapdisk based on
> http://wiki.xensource.com/xenwiki/blktap2

Yes, this is very unpleasant.  But at the very least I think you
should be somewhat more careful and at least expect the thing you eat
at the front not to contain slashes.

> Though as i noted in an earlier email, libxl doesnt accept tap2 while xend
> accepts tap2.

We have fixed that very recently - in the last day or two.

Ian.

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