thandy repository mirrorability

coderman coderman at
Thu Aug 5 01:16:21 UTC 2010

On Wed, Aug 4, 2010 at 9:03 AM, Peter Palfrader <peter at> wrote:
> ...
> I've been wondering about mirrorability for when we start using thandy
> for real.  That is, what happens when a user accesses a mirror that is
> in the process of updating its files.
> ...
> So, from a quick look at thandy and without knowing much about it, it
> appears as if thandy will suffer from much of the same problems.  The
> timestamp.txt file looks like one that's particular problematic.  Is
> this correct or is there some clever scheme that avoids the desync
> problems while a mirror update is in progress?

yes, this will have a similar issue. caveat being that at least one
repository has all the files needed, so the client will retry / resume
until success. (not always using a mirror like Debian)

this introduces other issues as one pet peeve of mine during the "use
Thandy as network installer" experiment was that an on-demand network
install would delay a while on failed attempts, while you really want
it to try again quick or bail out.

> Should we worry about this and try to see if we can come up with some
> clever schemes that mitigate or avoid the issue?

i am inclined to say ignore this unless it becomes a problem for these reasons:

- most Thandy clients will be doing background updates, and won't care
if they have to cycle to the next mirror because the current file is
incomplete or missing.

- the HTTP 1.1 resume capability in Thandy means even a partial file
can be useful, so avoiding these is not necessary and may actually be

note that my understanding of Thandy is rusty, and out of date.
hopefully Nick or others will correct my misstatements :)

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