Domestic Cat 5 cabling and management

[Pete Verdon]

No I don't.

My mobile never runs out of charge (I put it in a cradle in the car in order to listen to the music that's on it, and it gets charged at the same time). I guess it's possible that I could lose it or have it stolen, and then I could conceivably use the landline that I do have (after looking up the number I need in the backup on my computer), but it's hardly an argument for installing a PABX.

I also need a mobile for when I'm not at home, so why not use it?

===

I'm not for a moment suggesting that my situation applies to everyone. I wasn't trying to argue that people in general shouldn't use landlines. I was just making a good-faith attempt to answer "Appin"'s original question - why would someone install a decent network setup and yet not add a PABX for landlines? I have installed a decent network setup, but don't find any need for a landline for the reasons I gave. Seemed like a reasonable answer to me.

Pete

[Pete Verdon]

But if I was there, wherever "there" is, my landline in Southampton would be no use to me at all.

Pete

[The Natural Philosopher]

Nicely summarised, mate.

The temptation these days is uber RAM caching of disks, so that many reads, and all writes, take place to RAM only, with the disk subsystem trailing behind actually writing out the data in between times so to speak.

I had a shock untarring a 360Mbyte file yesterday...CPU at 3%, but 80% of all the RAM beig used by the program to dismantle chunks of data, and about half a minute in total to do it..during which time all the disk IO buffering was 'stolen' for use by the program ...

Defintely 4x RAM would have helped.

[The Natural Philosopher]

Bwahaha!

Flash is even slower on writes..

[Rod]

I mentioned flash being announced with a read speed of 220 MB/s. That story said a write speed of 200 MB/s. Which I think is pretty impressive.

[The Natural Philosopher]

However, flash has to write ENORMOUS areas all at once. You write it in whole pages. So changing one bit is like changing one bit in a disk with a half gigabyte sector..

It may indeed do 200Mbps writes, but if you have to do thee whole 200Mb to change one byte, it still takes a second..

[Andrew Gabriel]

Write-biased enterprise flash drives are fronted by DRAM caches, which then enable the flash controller to de-stage to the flash memory in a more optimal way. That claws back a lot of the performance. The flash controller can do quite clever things to remap logical to physical blocks to minimise the number of flash blocks which need updating (it's playing this game in any case for wear leveling and bad block remapping). I'm not familiar with the extent to which consumer grade flash products deploy such techniques but I would guess much less so as they have much shorter lives and lower performance.

[John Rumm]

If you use the right sort of plug, and you are not forever moving the cable, then cat5 solid is quite reliable IME when used like this. (its not bad using the wrong plugs either for static applications)

[The Natural Philosopher]

I know. I did it a few times..and then after crawling under a filthy set of racking and behind a dusty rack, to discover that one strand had broken,decided to give it up for Lent,.

[John Rumm]

Do you know anywhere to get suitable baluns at a reasonable price? (most seem to cost more than that of laying in a dedicated cable!)

[The Natural Philosopher]

Try black box.. used to get all teh odds and ends from them.

What baluns do you need.

[John Rumm]

None right now... but each time I have looked in the past they were typically £50 - £100+ per end, which usually makes running a co-ax or long VGA lead cheaper.

[Pete Verdon]

I've helped set up a CCTV system which sent composite video over maybe

75m of cat5 using baluns. They were IIRC about a fiver (not sure per pair or per end) from ebay, and I didn't think they'd work at all. Actually, they work a treat - no significant difference locally vs remotely. (The picture was poor either way because the cameras were crap, but that's a different matter.)

Pete

[John Rumm]

That sort of money would make it quite an attractive option...

[tony sayer]

I'm sure they'll be cheaper around than from Black Box !. Good outfit but rather expensive IMHO..

Theres a CCTV company New Concepts or RF concepts in Northern Ireland who do these .. not too expensive IIRC..

CPC I think have them too ....

[Andrew Gabriel]

Often in CPC's special offer leaflets.

[John Rumm]

last ones they had were VGA versions at about £50 IIRC...