So you have a website, and you want it to be able to survive aSlashdotting (these days probably as likely to come from Reddit, Digg,or something I'm too out of touch to have heard of as from Slashdotitself). Assuming that you're not going to blow your bandwidth (a saferassumption than it used to be; these days you can usually offloadpictures and videos to someone else), what usually takes sites down inthis situation is your web server getting overloaded with the

I've recently been thinking about what features we need for painlesslong term storage management , and in theprocess I've been thinking about what we actually do here with ourSAN-based NFS fileserver storage over time. Somewhat condensed, we seemto:

• add new storage units.
• replace existing old storage units with new ones, possibly with some consolidation because disk and thus unit capacities keep growingover time (so that it's not a one to one replacement of units).

  (We have relatively undemanding

How often have you seen a reverse DNS entry of host.dom.ain.10.11.12.in-addr.arpa. ? I've seen it too often, andI've even created them too often. Such incorrect reverse DNS entriesexist only because Bind makes it all too easy to shoot your foot off byinsisting on perfect consistency; for PTR records, as for all otherrecords, a name without a terminating dot is taken to be in the nameof the

When we set up strict overcommit mode , we hadto pick an overcommit ratio, or the alternate way of looking at it, wehad to pick how much total address space commitment we allow. Because wefirst did this for compute servers, we decided to size things so that anactive process would be able to use more or less all of the machine'sphysical memory, plus allow some extra on top to account for systemprocesses that would get pushed into swap.

The logic is relatively straightforward:

• on dedicated

This server recently moved from FedoraCore 2 to FreeBSD, and in the process I discovered that I had quietlybecome addicted to a few vim features, despite past dislikes of overly intelligent things that call themselves vi .

(I am pleased to report that the default FreeBSD version of vim does not behave that way .)

So it turns out to be necessary to set a few vim parameters to getit to behave the way I want. For my future reference, here's what I'vefound I need to

For reasons that do not fit into the margins of this entry, DWiki sometimes needs to get the current Unix load average. I developed DWiki on Linux, and getting the load average on Linux is really easy; you reada line from /proc/loadavg , split it into three floating point numbers,and you're done. So I wrote a get_load function that did that andforgot about the whole thing.

Then this server got changed from Linuxto FreeBSD, and suddenly that code didn't

Since I got asked this in a comment on my entry about clearing metadbreplicas , here is what I remember of how I managed toget a metadb replica so corrupted that it paniced Solaris 10u3 x86.

• I wanted to experiment with metasets on my test machine, so Ineeded a local metadb replica . Because Ididn't know about this I didn't have a spare partition, and becauseI didn't know any better I put the local metadb replica in thattempting slice 8

There is a movement for the default configurations of things like exim to defer sender verification to RCPT TO time;instead of reporting an error or a defer after the MAIL FROM , all MAIL FROM s are accepted and only later does the message start gettingerrors. I have recently come to a realization about why this is wrong,and I even have an example.

The problem is that when you give at least a 4xx error to an RCPT TO ,it makes the sending mailer think that there is a problem with

Here's some somewhat sketchy notes, mostly for my own future reference,on various bits of booting Solaris 10 x86 into single-user mode.

On x86 Solaris, kernel boot parameters go on the end of the ' kernel/platform/i86pc/multiboot ' line in the GRUB boot entry. You put them inby interrupting the GRUB menu to edit the default boot entry (and thenthat line). The two most useful parameters are -s for single-user