Re: Audacity and Gentoo

On 2006-01-18, Nix <nix-razor-pit@xxxxxxxxxxxxx> wrote:

> AIUI, if you *possess* a device capable of receiving broadcast TV
> signals, you must pay, whether you use it or not.

In the uk legal groups, the question is frequently asked and the
position is apparently that as long as it's not capable of receiving a
picture then it's OK, e.g. there are no aerial leads or even if the
power plug has been chopped off. It's one of those areas, like
business tax registration, where the powers that be decide that we
have to comply with laws that we're not allowed to look at in case we
manage to fall outside the remit.

> But I thought the magic TV licensing detector satellites spot anyone
> who so much as thinks about television but hasn't paid their license,
> and surrounds them with an exciting glowy spotlight that follows
> them everywhere! Don't tell me that's not true!

No, that's Ready Brek you're thinking of! Made from wheat grown
around Sellafield.

> Last I checked there was ~2s delay at the BBC end, but this may have
> changed. (I'm not sure what's happening in that time.)

Yep, it's changed, I've never noticed any delays on normal analogue
radio, I don't know if there's any delay on the "enhanced" digital
services, it wouldn't surprise me. I know there's a delay on the
internet streaming services.

> Aha! (Never having spent much time in server rooms, this sort of thing
> is somewhat opaque to me.)

Once the sides are removed, it's basically a bottom, a top, four
supporting posts and a set of shelves containing computers. There are
ample attachment points for cable-ties and grooves for cables to be
run in.

> Switches are so cheap you might as well replace it. I saw one on sale
> at the TCR fair last Saturday for a fiver...

Sure, but there's good ones and bad ones and given that I have no need
to change at the moment, it's hard to get any cheaper than £0.

> What's the UPS, btw? I'm getting more and more brownouts and flickers,
> so a UPS might be a good idea (assuming it doesn't cause more problems
> than it solves!)

It's a big APC Smart-UPS given to me by a friend, it was totally dead
even when plugged into the mains, but these things run their logic
boards off the batteries so if the batteries are allowed to run
totally flat then they will appear to be completely dead. I took the
batteries out and recharged them using a car charger on trickle charge
and it was fine after that.

I'd recommend APC Smart-UPS devices, but I intend to try MGE as well,
they maintain the NUTS Network UPS Tool Suite which I use, it supports
a large variety of UPSes but MGE are one of the few manufacturers who
directly contributed to it, and have taken it over now that the
original maintainer has moved on.

Misco, Insight and Hardware.com seem to all be pretty competitive,
sometimes they're £50 or so apart on some versions, often one site
will be cheaper than the others for the rack-mount, but more expensive
than the others for the floor mount, and vice versa, which is odd.

As for the UPS causing more trouble than it solves, I've not had any
problems other than my own left-footedness, e.g. thinking I'm telling
the UPS to do a self-test when really I'm telling it to power off the
load without warning.. Or plugging a non-APC serial cable into the
port labelled "rs-232" on the UPS, which makes it immediately power
down (hardly my fault though, damned misleading labels).

> Oh. OK. I guess I can't worry too hard, as at the last house we had
>
> - a lava lamp
> - a 486
> - two Pentiums
> - a Sun workstation
> - a printer
> - a modem
> - two desk lamps
> - three monitors
> - and a mousetrap

An electric mousetrap?

>> Ah the joys of reading alt.binaries.pictures.erotica.unix from bed!
>
> *boggle* does that group exist?
>
> ... no. damn, its contents mght have been amusing.

It does exist, just not on your server. Last time I looked there were
binaries of war-time erotic postcards, fat women showing their calves
and all that racy stuff!

> Need? What's this need stuff? I got a Sun because the SPARC is a nice
> CPU, not because I *needed* it. You'll find a use :)

Sparcs are too noisy, I've got an old one in the loft, one of the
Ultra range, sparc-based, can't remember the details. I think it's
about 1MHz with 2 bytes of RAM.

> How do you get rats and mice in your loft? They can't go up inside the
> walls; there *is* no `inside the walls' up there. Even the last house I
> lived in, with its built-in rat runs, didn't have rats in the roof. (It
> had them everywhere else, though. *shudder* that was a horrible place.)

>From the pile of dried *** up there, I suspect that I had bats at
some point and they roosted above a certain point, I have found one
nibble on an old box but the scurrying I used to hear has gone now
that I use the loft more. Out here, rats are going to be around, I've
not seen any but they're certain to be somewhere. I had a badger
peering through my patio doors once, I hope I don't have any in the loft!

> Nowhere near as convenient as a book, nor is any screen yet as nice
> as paper. I'm slowly cataloguing my books: I'm sure I have >3000 and
> maybe >4000 by now. (I'm perennially short of space for them.)

I've got about 30 books and three newspapers on my Palm, and I can
easily hold the palm and turn the pages with one hand, which is useful
when slouching around on the sofa so I don't have to move the other
arm. Mine's a T3, so I can turn it sideways for a 480x320 backlit
display, easily good enough to read properly with. Actual paper books
are OK but the Palm is preferrable to me as I have it with me at all
times, can download new books over GPRS, fit lots of books on it and
don't have to fumble about turning pages or trying to read around the
curve at the binding. Reading for 2 hours eats about 15-20% of the
battery, which is fine.

> Yeah. Their last attempt (the elibris, I think it was)

Librie. Supposedly only sold in Japan but I saw one in the window of
the Sony shop in Basingstoke, I must go back in sometime and have a
proper look at it, the display is supposed to be excellent although
the newer generation are even better.

> was so heavily restricted that in the end they had to release a
> crack for it to disable all the restrictions before it would sell
> more than a dribble...

I'm not sure it was Sony who released the crack, they wouldn't even
release it in English at first, not sure if they ever did.

epaper.org.uk has news on developments, including a new European model
coming out in April I think, which is designed to be open. Made by
irex, http://www.irextechnologies.com/

To be honest though, the Palm is easily good enough and is much
smaller, it can fit 60 characters across by about 20 lines down using
Plucker and the backlight means no problems in dim light.

> Ah, right, you can get bits and pieces as well. I might just do that :)

xmame executable is about 15 meg, but still it doesn't add up to much
space. I've just managed to get my cabinet/"tv" going again after
upgrading the whole system, bloody nvidia drivers causing problems.
I'm glad I didn't buy the cards, but it's a shame those are the only
ones I have around that would fit the machine as I'd like to break
them in half with a pair of pliers.

> bwahaha. Online games are *not* distributed simulations!

They are, but of really simple environments ;-)

> Another major trick is limited visibility and things like that; the fog
> looks very atmospheric, and also means that only a few spatially-local
> nodes need to communicate much. Military sims oddly have to allow
> simulations of warfare even in places where it isn't foggy.

Sure but that's just generic graphical tricks, not related to
distributed systems. Most games just design the worlds with
restricted views, so walls around buildings, no large halls,
racetracks with lots of ups and downs etc.

> Its difference-storage is much more primitive than that. If you have a
> file of version N checked out, and you write() to it at some block which
> was last written at version M, that block gets copied forwards to
> version N and then overwritten (appropximately). There's no `diffing' at
> all: in fact there's the opposite, a propagator thread that finds blocks
> that are heavily read but are far in the past and pushes copies
> forwards. This is critical when you consider e.g. logfiles, the starts
> of which may be ten thousand commits old, or directories; since each
> link()/unlink() is a commit, without the propagator thread an ls of
> a large directory would have got *slow* in time...

Still, a difference system would save a lot of space, unless database
overheads make small stores inefficient, which they probably do.

> I considered storing everything with the whole file at the front and
> generating reverse block deltas, like RCS does, but that has two major
> problems: firstly it interacts rather badly with branches,

<imagines problem> Ouch ;-) How about a reverse system with
checkpoints which store the whole file at the point before the branch?
It would also be useful in case of data recovery as you'd at least be
able to recover the whole file at a checkpoint. (I'm paranoid about
losing data to complex databases as you can tell).

> TBH I doubt I'll ever migrate this system from a database to direct
> block writes. There's so little point, and the database will let me do
> nifty stuff later on with very little efford, like optional
> near-instantaneous full-text search of selected directories, automatic
> replication and on-the-wire encryption, automatic compression of large
> blocks... I've even got a mad idea for an index type that indexes images
> as edge-detected vectors, so you could scribble a rough image and get
> shown the images most like it :)

Hehe, image searching would be interesting. Last time I saw something
similar was on a product dubbed "pornsweeper" that a company I worked
for used to sell, we sold it to a railway contracter and found that it
blocked pictures of trains...

Image processing though is extremely maths intensive, so I hope you're
happy with heavy maths, I know I get bored and start thinking about
other things so my dreams of writing a sound processing system (about
as complicated) foundered pretty quickly.

> Yes, I've written several. In fact I was considering making the
> low-level table-update crud in this system by using PL/Python, but I
> think on reflection I'm going to stick with client-side C for now.

It's not so much self-written python that never works, it's the
packages that people produce that seem to bork far more often than I'd
like so I tend to avoid anything written in a scripted language.

> Well, PostgreSQL has several recovery mechanisms. I've had slight
> problems once before when one postgres background process forgot to die
> on schedule, and ended up running at the same time as a new instance,
> writing to the same database: the first recovery mechanism I tried
> worked.

I certainly hope it has, I've just started using it so haven't gotten
to grips with it yet having been a mysql user previously. I've had a
few problems with mysql.

> There is no need to do that: see chapter 23.3 of the manual (`Online
> Backup and Point-In-Time Recovery'). There are calls in PostgreSQL
> that you can make to dump files into the write-ahead log directory
> indicating when the backup started or finished, and the idea is that
> you tell PostgreSQL a backup is starting, back up the raw datafiles
> with tar or something like that, tell it the backup is over, and
> then the existing WAL archiving system takes over and backs up all
> write-head logs from the start of your backup to the present
> moment, as they are generated.

Sounds interesting, I've got "database backups" down on my todo list
for next week, I expect I'll probably replicate the database from the
main backup server to the secondary backup server (the backup server's
database is what I'm trying to back up, currently I dump SQL). That
way I'll be able to easily recover the backup server if it dies (as it
has in the past).

> Not if all the data is replicated to at least one other machine.
> (Critical data should probably be replicated to each machine.)

I prefer to keep my computers as simple as possible, in an emergency
it's easier to get back on your feet, as I found some time ago when
the company I worked for got raided and half the computer room
contents got knicked. It took us about 2 hours to bring customer
servers back online by building machines from scratch and combining
them all onto the few servers we had left.

> Wow. I'm just backing up to CD-R[W] here...

Yeck, I use DAT and backup diffs every morning automatically, I only
have to change tapes once a week. 4 months' worth of backups, from
which I can recover the state of a file on any given date, CDR backups
are too labour-intensive to the point that doing it every day is a
PITA. You could I suppose backup diffs to a CDR that's left in the
drive all week but tapes are cheap and once it's been written it can
be removed and safely stored, unlike the cheaper but more dangerous
idea of backing up to something like a USB disc.

> Yep, I've done that :) I've also got an `auto-rebuild this machine from
> source' option; I'll be using it in a month or so, when GCC 4.1 is
> released, to rebuild my firewall using the newly-reimplemented
> -fstack-protector-all and FORTIFY_SOURCE simultaneously. (Think
> `automatic overflow protection for strcpy() and friends', as well as the
> generalized probabilistic protection against stack overflow which
> -fstack-protector-all offers...)

Yeah and watch half your packages fail to build ;-)

While updating my arcade cabinet, at least one system package in there
printed a warning about it requiring executable stacks (!), can't
remember what it was. I prefer to let others test out new versions of
GCC before upgrading, and adding stack canaries etc in is bound to
bork a fair few packages. I can remember "Immunix", nice effort but
not convinced that kind of thing is worth the effort, SE-Linux on the
other hand I like, and must check it out again, I last looked in 2001
or thereabouts.

> This is generally true of any thread with me in it, I'm afraid :(

Ditto, perhaps in future we should agree to stay out of each other's
threads ;-)

--
Blast off and strike the evil Bydo empire!
.