dan schrieb:
> amen Les
> no need to have just 1 backup server!
> 
> with 8GB of ram, I would give a rough estimate that you can have up to 
> 500,000,000 files in flight at one time as far as ram is concerned!  
> that includes ALL hosts that would be backed up simultaniously.  I doubt 
> RAM will be an issue for you.  Probably hard disk speed will be the big 
> hurdle here.  You have some pretty limited options here because you will 
> spend BIG BIG money getting a very fast RAID5/6 hardware array while 
> regular desktop drives will perform pretty poorly with a software 
> RAID5/6 because having the CPU do the checksums adds a lot of latency 
> with = poor write speed for large numbers of small files aka hard links 
> and directories aka 90% of what backuppc does.

Err, no.
CPU load because of RAID5/6 computations on today hardware is marginal.
RAID5/6 have a performance penalty when compared to other RAID level 
because every single write (or, write IO operation) requires four disk 
IOs on two drives (two reads, and two writes), possibly harming other IO 
operations.


> just take Les' advice, split up the backup job among a few servers 
> instead of one BIG one.

I guess he meant splitting one big backup job into several smaller 
(i.e., instead of backing up 1x350 GB, backup 7x50 GB, all that to one 
BackupPC server) - it is always a good idea for large backups.



-- 
Tomasz Chmielewski
http://wpkg.org

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