Am Donnerstag, 7. Juni 2001 09:27 schrieb Robert Davies:
I don't know what adsm backup is but I haven't noticed any respondes, I'll make some general observations.
adsm is a commercial multi-platform backup suite with server and client side.
I have set up a firewall (susefirwall 4.3) between the internet and our internal network. One thing I have noticed is that the backups have slowed down by a factor of 10 !
With a non-trivial ipchains ruleset I still had an ftp throughput of 10MByte/s on 100Mb/s network. Can you check your basic ftp throughput?
ftp throughput is nominal ( 1-3 Mbyte/s ). Http seems ok too. Thats whats bugging me, it seems specific to the backup. The hardware should be more than up to the task, the computer used is a dual pentium 200Mhz system. The load on the system is never higher than 0.3.
Have your NICs managed to negotiate the network speed down from Fast to Good ole' Ethernet? Anything new go into a non-switched 100Mb/s Fast Ethernet network that could cause fallback to 10Mb/s?
How could I check that ? (Sorry for this stuipid question )
adsm needs port 1500 and uses a tcp buffersize of 16k. One thing I noticed
is
the both interfaces show many collisions. This is the output of ifconfig
By my calculations your collision rate is insignificant (< 0.5%) 11896 * 100 / 2487098, however to get meaningful results you need to make the calculation :
(Cf - Ci) * 100 / (Tf - Ti) <= r%
Where Cf and Tf are the final collisions and transmissions, Ci and Ti are initials, and r% is the acceptable collision rate. Note initials at beginning of backup run, and finals at end.
Your error rate seems somewhat high, but again as a percentage it is rather low.
One thing i have noticed is that the error rate grows faster (faster as in errors per transmitted packet not error per timeunit) during backup then during normal operation of the firewall.
If your tcp window size is not large, then you may be dependant on the round trip times, Novell Netware was very prone to this problem in early versions, whereas a modern TCP/IP implementation will perform fairly well on a 'long' but 'broad' pipe.
the adsm backup machine is in the external network, connected via a
100Mbit
ethernet card and the machines that are backed up are in the DMZ, also connected via a 100Mbit ethernet card.
This strikes me as being rather peculier, backup is mish critical, I've often built 'server' backend networks linking machines in the DMZ specially for backups, to do them to an 'external' network, rather than an internal one seems strange.
The backup of our departments computers are done by a central authority of our university. I have no influence on the location (neither physical or in adress space) of the backup machine :-(.
That said, how are you buffering your tape drive? Many drives slow considerably if you cannot match their streaming rate, there is a command 'buffer' in the non-x application series, which allows efficient buffering, and with a high -p %, and a large size -s 16M, you can ensure the drive will be driven at it's streaming rate.
I have no information on the hardware used to backup the data, but will check on that. But before installation of the firewall the backup speed was approx. 2 Mbyte/s now it has slowed down to a few hundred kbytes/s. Thanks for the help, Alex.