load balancing among mail servers
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From: Massimo Nuvoli on 16 Feb 2010 10:39 donovan jeffrey j ha scritto: > > On Feb 16, 2010, at 8:09 AM, aa wrote: > >> Someone advised me to insert in the DNS zone a list of MX records >> defined with the same level of priority so the DNS server will choose >> one of them without invoking always the same mail server.... >> It could be an idea, in my opinion, but I'd prefer a "less random" >> solution and a more scientific one.... > very easy for smtp relays. > smtp1 > smtp2 > create a dns name smtp, and your system will round robin query for the > next available server. DNS round robin is bad, it works but is defective for real load balancing. The client choose the IP to use, this is "random", and after can use the same ip for a while... this is not random. The real solution is lvs or keepalived, the choice of the node is done by the load balancer... Bye.
From: Banyan He on 16 Feb 2010 10:45 Depends on how many public IP addresses you have. I'd like recommend you to have a try with keepalived. It's the balancing service software. Open source. The front-end service keepalived will handle TCP request and forward to the back-end servers you have. You can also setup the filter also. Pretty nice. On 2/16/2010 9:09 PM, aa wrote: > Hi, > I need to create an infrastructure that allows to divide a list of > mails to send among a series of postfix mail servers. > > For example, I imagine this situation so : > I install a series of postfix mail servers and when it's necessary to > send a mail it's enough to send it to an IP address that the actual > delivery of the mail is delegated to a server that has the lowest > charge of jobs... > > I'm wondering if a particular configuration of postfix can be useful > to resolve this issue... > > Someone advised me to insert in the DNS zone a list of MX records > defined with the same level of priority so the DNS server will choose > one of them without invoking always the same mail server.... > It could be an idea, in my opinion, but I'd prefer a "less random" > solution and a more scientific one.... > > Thanks for every suggestion you'll send to me.... -- Banyan He Information Security& Infranstructure Technology Blog: http://www.rootong.com Email: banyan(a)rootong.com
From: donovan jeffrey j on 16 Feb 2010 10:47 On Feb 16, 2010, at 10:39 AM, Massimo Nuvoli wrote: > donovan jeffrey j ha scritto: >> >> On Feb 16, 2010, at 8:09 AM, aa wrote: >> >>> Someone advised me to insert in the DNS zone a list of MX records >>> defined with the same level of priority so the DNS server will >>> choose >>> one of them without invoking always the same mail server.... >>> It could be an idea, in my opinion, but I'd prefer a "less random" >>> solution and a more scientific one.... >> very easy for smtp relays. >> smtp1 >> smtp2 >> create a dns name smtp, and your system will round robin query for >> the >> next available server. > > DNS round robin is bad, it works but is defective for real load > balancing. The client choose the IP to use, this is "random", and > after can use the same ip for a while... this is not random. > > The real solution is lvs or keepalived, the choice of the node is done > by the load balancer... > > Bye. > <massimo.vcf> I wouldn't say it's bad, it's just cheap. Of course a load balancing switch can be purchased $ -j
From: Eero Volotinen on 16 Feb 2010 10:53 2010/2/16 donovan jeffrey j <donovan(a)beth.k12.pa.us>: > > On Feb 16, 2010, at 10:39 AM, Massimo Nuvoli wrote: > >> donovan jeffrey j ha scritto: >>> >>> On Feb 16, 2010, at 8:09 AM, aa wrote: >>> >>>> Someone advised me to insert in the DNS zone a list of MX records >>>> defined with the same level of priority so the DNS server will choose >>>> one of them without invoking always the same mail server.... >>>> It could be an idea, in my opinion, but I'd prefer a "less random" >>>> solution and a more scientific one.... >>> >>> very easy for smtp relays. >>> smtp1 >>> smtp2 >>> create a dns name smtp, and your system will round robin query for the >>> next available server. >> >> DNS round robin is bad, it works but is defective for real load >> balancing. The client choose the IP to use, this is "random", and >> after can use the same ip for a while... this is not random. >> >> The real solution is lvs or keepalived, the choice of the node is done >> by the load balancer... >> >> Bye. >> <massimo.vcf> > > I wouldn't say it's bad, it's just cheap. Of course a load balancing switch > can be purchased $ Well, It is bad because server (client) can cache ip address for long time and then one of your smtp server fails. It can take long time before server gets ip address of working smtp server.. -- Eero
From: Wietse Venema on 16 Feb 2010 11:01
Massimo Nuvoli: > donovan jeffrey j ha scritto: > > > > On Feb 16, 2010, at 8:09 AM, aa wrote: > > > >> Someone advised me to insert in the DNS zone a list of MX records > >> defined with the same level of priority so the DNS server will choose > >> one of them without invoking always the same mail server.... > >> It could be an idea, in my opinion, but I'd prefer a "less random" > >> solution and a more scientific one.... > > very easy for smtp relays. > > smtp1 > > smtp2 > > create a dns name smtp, and your system will round robin query for the > > next available server. > > DNS round robin is bad, it works but is defective for real load > balancing. The client choose the IP to use, this is "random", and > after can use the same ip for a while... this is not random. This is a technical mailing list. When you claim that something is bad, you need to support that claim with actual evidence. Otherwise, you are just spreading rumors. How many clients hang on to a server's IP address? How many of these hang on to the same server IP address? What evidence is the basis for these claims? Wietse |