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Jan
29
comment How to configure ntpd to sync time more frequently?
@RomanGaufman and I'm pointing out that you're asking ntpd to do things it's not designed to: The ntp daemon disciplines the local clock. It assumes your network connection will be stable and your local clock will remain within a sane window if the network dies. It re-synchronizes with the time servers after a network failure if the time delta between the local clock & the time server is still sane, but if not it will fail because It doesn't (and can't) know if your clock is bad or the time server is. If ntpd behaved as you suggest it could do a huge amount of harm in the pathological case.
Jan
29
comment Apache stability on a VERY high traffic server
@StarWars The best answer I can offer is "Test it and see" - It depends on what your environment is doing, but if you're not having any problems you can probably defer making changes until your analytics start pointing at something that needs to change…
Jan
29
awarded  Taxonomist
Jan
28
comment How to configure ntpd to sync time more frequently?
@RomanGaufman You're asking ntpd to do something it's not designed to do (fix a clock that's wildly incorrect). You should run the ntpdate command (with the -b option) to set the clock initially, and then start the NTP daemon to maintain it (this can be part of your internet up/down scripts). If your connection or power are wildly unreliable you can also run ntpdate out of cron every 5 minutes, which may give "Good Enough" clock accuracy. (You may also consider investing in a hardware clock for your Raspberry Pi as an alternate solution. Google can help you find resources for that.)
Jan
26
awarded  Yearling
Jan
22
comment Load Balancing long running TCP connections
@BobAman Yup, 4+ years ago when I wrote this HAProxy wasn't as big a thing but if I were implementing this today I'd give preference to doing the load balancing in HAProxy (because of its other capabilities like leastconn to assign new clients to the servers with the fewest connections) and make pf or similar my second choice.
Jan
21
awarded  Enlightened
Jan
21
awarded  Nice Answer
Jan
20
comment Sudo as different user and running screen
@sudo In order to do its thing script opens its own tty device, owned by the user who ran it (look in /dev and you'll see it appear after you run script). screen then grabs that tty device (which is owned by the user running screen so it has no trouble accessing it). It's a total hack job, but it works. Looking at some of my machines it appears new versions of screen seem to install setuid-root, which also works, but means you have another setuid-root binary floating around, which makes some folks justifiably uncomfortable.
Jan
20
comment How are SMART selftests related to badblocks?
@endolith The tests are not direct equivalents, but the purpose they serve is equivalent (discover and allow the remapping of bad sectors). My main point was the last paragraph: if you want to run badblocks as a disk exerciser (to see if you can provoke SMART errors because it's finding a bunch of bad blocks) go for it, but if you're running badblocks today with the intention of then loading the bad-block list to avoid using those sectors (as we did in the stone age) you're Doing It Wrong: Visible bad sectors mean you should chuck the drive in the nearest trash bin.
Jan
20
comment Does Ubuntu Server have any sort of cron job to automatically clear /tmp?
@guettli Lots of reasons: Because it's good practice. Because /tmp isn't a magical infinite pool and 1000 scripts all leaving their detritus in it can fill the volume (which breaks things). Because it doesn't take appreciable time to clean up your temporary files (do it right before you exit, no different than clearing a lock that prevents 2 copies of a script from being run). Because guessing that a temp file is OK to delete just because it's X days old is a kludge that can in fact break things. I can go on if you'd like…
Dec
16
comment Why is “chmod -R 777 /” destructive?
@Deji everyone is defined as the union of set including the user who owns the file, users in the group which owns the file, and users who do not meet either of those criteria (literally the three octal permission digits: User, Group, and Other). In other words any user with access to the system. ("Access" in this context could be a shell account, which is how I would normally address it, but it also includes access through a web form/CGI which writes data to disk: The www user can now write to any file on the system, which means random visitors can too.)
Dec
8
awarded  Enlightened
Dec
8
awarded  Nice Answer
Nov
30
revised How do I 'activate' voicemail on an extension on asterisk-Freepbx
deleted 27 characters in body
Nov
25
revised Can you help me with my capacity planning?
It's trivial, but fixup formatting & correct a long-standing spelling error.
Nov
5
awarded  Good Answer
Oct
13
awarded  Enlightened
Oct
13
awarded  Nice Answer
Oct
4
awarded  Nice Answer