On Thursday 23 January 2003 15:20, Jon LaBadie wrote:
>On Thu, Jan 23, 2003 at 02:46:07PM -0500, Scott Mcdermott wrote:
>> Jon LaBadie on Thu 23/01 02:34 -0500:
>> > >    - amanda can't do hardware compression without breaking
>> > > easily
>> >
>> > False.  Many use hardware compression very happily.  The issue
>> > is that DLE's vary greatly in their compressibility.  Some of
>> > mine compress to 20% of their original size, others to 95%. 
>> > For some tasks, amanda would like to know how much tape a
>> > backup is going to use.  If she doesn't compress it, she
>> > doesn't know for sure.  But she certainly does not break.
>>
>> ok "for some tasks" like what? If it doesn't break I'll probably
>> opt for
>
>planning, whether to do a level 1, level 2, or level 0 backup. 
> When HW compression is used you will give a single
> "compressibility" factor for her calculations.  That will only be
> accurate for some DLE's.
>
>After a dump is done and in the holding disk, "will it fit" on the
> current tape is also hard (impossible) to determine with
> certainty.  So you give her an "approximate" capacity, guessing
> at an average compressibility and she uses the actual dump sizes
> (precompression) and that guessed total capacity in her
> calculatons for "will it fit".
>
>> hardware compression, since that is a really big win for my
>> particular site, and if I am using RAIT I get 4 ASICs working on
>> it rather than one slow CPU :)
>
>So do it, lots of people do.
>
>> > >    - amanda doesn't do parallel backups under any
>> > > circumstances
>> >
>> > Not sure what you are looking for in parallelism.  Certainly
>> > amanda can simultaneously backup multiple DLE's from a single
>> > or multiple clients.  Amanda can't run multiple configurations
>> > (say a daily and a monthly config) at the same time.
>>
>> I mean multiple drives.  Looks like RAIT is the answer here. 
>> This feature is apparently backed out of the 2.4p2 RPM I have
>> from Redhat 8.0; the ChangeLog note says "instead, in 2.5 and in
>> 2.4 multitape" so this is why I did not come across it before.
>
>Don't go with pre-built packages.  Get the current 2.4.3 source
> snapshot and build it yourself.  RAIT was introduced in an early
> beta for 2.4.3.
>
>> Amanda sure is a lot different than Legato Networker, which I am
>> switching from :) But since we could probably pay enough full
>> time workers to record all the bits needing backup onto a paper
>> with a pencil, for less than it costs to keep Legato, I think
>> I'll not mind a few setbacks on the way :)
>
>Several years ago I moved two clients from Networker (Sun's
> version). They have never looked back.  One client in particular
> was pissed at Legato's claim (at the time) that because the
> backup host had died, there was no way to recover any of the
> existing backups.

'scuse me Jon.  If I was that client, paying thru the nose and got 
that reply, I think my next call would have been to the lawyers.   
They have a certain amount of responsibilty to facilitate recovery 
from *any* failure, after all, thats what you are paying them for.  
Thats in-excusable for a commercial product to have that kind of an 
attitude.  But then I think, from my conversations with knox, that 
knox would probably be a somewhat nicer situation.  Can anyone 
testify any differently?  OTOH, if you can get one of their tapes 
into a drive that will read that tape, all the stuff to do a from 
scratch recovery is actually on the tape itself as a lengthy header 
that you can dd back, uncompress and run to get the rest of it.  On 
every tape, just grab one and go.

If Legato isn't doing a similar theme, yucchh.

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.22% setiathome rank, not too shabby for a WV hillbilly