On 10/12/07, Richard L. Hamilton <rlhamil at smart.net> wrote: > > 3) Install in single user mode and/or reboot after > > installation (very commonly over-cautious advice) > about dependencies of the earlier incarnation anymore, do I?). As > to the third point in particular, I would suppose it depends on one's > imagination as to what's overcautious and what isn't, but if and when > everyone has zfs root and promotable clones become part of patching, > wouldn't it be a matter of dividing up patches that didn't need a reboot > and whose benefits were needed immediately and which were very > low-risk from the rest, and doing the first bunch conventionally and the > second bunch via a clone, and scheduling the reboot that switched clones > at one's convenience?
I am thinking of the situation where you need a fix to a particular problem that really doesn't require reboot or single user mode and this would be fairly widely agreed upon by competent developers. A key recent example is telnetd, but I've also had the same thing for patches that replaced single binaries like iostat and vmstat. The difference for such a patch that has huge impact is: "I need to apply this patch. It will take 5 minutes and there will be no interruption to service. There is extremely low risk that this will affect anything on the system." vs. "I need to apply a patch that requires a reboot. This is the database server for X that affects several app tiers. While it is down, we will be unable to perform many functions required to keep factories running. The outage will last about 1 hour." That is: 5 minutes of a sysadmins time during the middle of the day (plus light change control activity) vs. hundreds to thousands of man hours of lost productivity because a critical system is down during work hours or fewer lost man hours and a sysadmin gets to put in some more OT. -- Mike Gerdts http://mgerdts.blogspot.com/
