From: "Jeff Waugh" <[EMAIL PROTECTED]>
> On Tue, 2003-06-24 at 04:04, Oscar Plameras wrote: > > It is also a good idea to take the /usr/local/sbin/named > > away to another FreeBSD/Linux box. DNS lookups is > > always a slow process and queues other processes > > particularly during Internet peak hours. > > > > Because the box is mainly Email services, and not > > transaction type application such as financial databases, it > > will help alleviate processing bottle neck by increasing > > the time between disc sync'ing as done by the (syncer) > > process. > > It wouldn't be a good idea to shift DNS away from the email server - > much of what an MTA does is DNS lookups, so it is always a good idea to > have a fast, caching name server on the local machine. Better throughput > through better latency. > > Caching (or authoritative, for that matter, on an unbusy domain) DNS > isn't a horribly expensive process. > True, email services is dns service intensive. It demands both forward and reverse lookup services. So, when MTA requires DNS services it is serviced by named in the same box. First, the catch is, named is less important in this particular box with 0.0/1.6 percent CPU utilisation. Sustained CPU activity is more important for the main task done by spamd as indicated by 78.1/14.7 percent CPU/MEM utilisation. The fact that named has far less activity in this box is perhaps due to spamd being so aggressive and leaves little time for other processes to spawn when it should. By moving it to another box within the same network may make both named and spamd happier and livelier. Secondly, with named servicing the MTA in the box, it also answers service request from other services outside this particular box. It is that time that the DNS in this MTA box spends servicing others that we do not wish to loss in view of the capacity requirements for CPU utilisation by spamd. The advantage of named being in the same box as the MTA is negated and lossing more. It sounds to me like this network is rather busy with a number of domains and users being served. 60Gb of email data in a day alone tells the story. -- SLUG - Sydney Linux User's Group - http://slug.org.au/ More Info: http://lists.slug.org.au/listinfo/slug
