[vdr] Re: OT: 149 GB Maxtor disks.

[Usenet-372112@zocki.toppoint.de (Rainer Zocholl)]

Emil.Naepflein@philosys.de(Emil Naepflein)  20.10.01 11:45

Once upon a time Emil Naepflein shaped the electrons to say...

>> P.S. This gets seriousy offtopic. Maybe we should continue this
>> off-list.

>I think this is not totally offtopic, 

ACK. Because "recording" required some disc and in a not
yet usual way/amount..

>because more people may run
>systems with raid to prevent loss of their permanent recordings. 

But please do not mixup any kind of RAID with "backup" !

Most data lost are, are you already wrote, not caused
by a disc (hardware) failure. Most data lost are caused by the 
application software (remember the timer.conf lost we had
if the video disc was full) and far most often by the user(s)...
Against this RAID can't help, it only deletes faster if the
user types "rm -f * .bak" (pay attention to the -unintended- 
blank after the star. Don't say: "That will never happen to ME"
(I don't mean anybody personally!)
I saw a guy who typed "del *.c" on a network drive.
He wanted to do just a "dir *.c" ... shit happens..


>You say that such a configuration is not totally secure against data
>loss - I agree. I say I know the risks and point of failures and can
>recover from some of them without loss, from most with partial loss.
>And hey, this is no life critical data, it is just movies which are
>repeated by the stations from time to time anyway. ;-)

As more hardware is involved as larger are the 
chances of failures. If one spreads it's data over more than
one disk, he got the speed adavantage, but the 
disadvantage, that if one disc dies, the intact data fragments 
on the other disc do not help much...
RAID-5 makes sense only together with "hot swapping" and if
taking the server offline would become too expensive because
hundred of peoples can't work any more.
RAID-0 makes sense if one needs disks speeds that is
far larger than those a single disc can give.
Normaly those data are not kept on the RAID-0 of a longer 
time because a full disc is slower than an emtpy (sound silly 
on the first view, but is true because the operating systems needs 
more time to find a free block and the blocks are spreaded of the 
disc too) and the RAID-0 is too "expensive" to do "backup".


The idea making "backups" with disc is OK and good.
(One 40GB DLT tape costs the same as or meanwhile more than 
a cheap IDE disc but is slower...). But not via "RAID" because it have
no hierachical system to keep older copies.
(The new copy might have the length 0...)

And: i saw one "professional" (=expensive) PC which kills his 
-entire- electronics by overvoltage on +5V by a broken main supply 
mainboard, cpu, and discs: all dead...only the fans survived...
Nice to have a tape in a save loaction...



Rainer