Re: Clock drift problems
From: Bill Unruh (unruh_at_string.physics.ubc.ca)
Date: 01/19/04
- Next message: Jeroen Geilman: "Re: Samba 3 Replace Windows PDC and BCDs?"
- Previous message: Bill Unruh: "the round() functions seems to be totally broken"
- In reply to: Allan Cady: "Clock drift problems"
- Next in thread: Christopher Browne: "Re: Clock drift problems"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Date: Mon, 19 Jan 2004 03:44:35 +0000 (UTC)
allancady@yahoo.com (Allan Cady) writes:
]Disclaimer: I'm asking this question about a Linux box, which I use
]only as a client of a couple of web-based applications and as a file
]server. I know almost nothing about Linux, or Unix. I'm a Windows
]guy. So please go easy on me!
]The problem is, on this Linux machine (Red Hat, I don't know what
]version), the real-time clock has gotten 7 hours slow. The guys here
]who administer this machine seem to be stumped about what to do about
]it. (This boggles my mind.) There are two problems: how to get it
]back where it belongs, and how to prevent it from getting out of sync
]in the future.
]The explanation I'm given about why they can't just "set the clock" is
]that there are applications that would wig out if the clock all of the
]sudden changes by 7 hours. I can understand that, but things like NTP
]are supposed to be able to deal with this kind of thing by adjusting
]the clock slowly over a period of time. I don't know the details, and
]I certainly don't know how to set this up on Linux. And I don't know
]if it's capable of handling such a gross correction.
]The explanation I'm given about why the clock is losing time so badly
]in the first place (about 15 minutes a week), is that it happens when
]we do our weekly backups to DVD-ROM; something is locking out the
]hardware interrupt that makes the clock work. Is this "normal"? They
]claim it's nothing to do with Linux, that it would happen with Windows
]too. I've never seen anything like this happen on Windows... DOS
]maybe, but that was 15 years ago. This is a Dell PowerEdge 1600
]machine, less than a year old.
]Given my ignorance of Linux, it's hard for me to ask specific "how do
]you do this" questions... for starters, I'm mostly looking for a
]general opinion of whether this problem is really as confounding as my
]buddies think it is. It may get to questions of "how can we configure
]NTP to do the gross correction without breaking applications", and "is
]there any way to fix the system so that the clock doesn't drift when
]we're doing backups", but to start with, I'd just like to know if I
]can believe the guys who are telling me there's nothing we can do
]about it. Or if maybe I can point them somewhere... tell them, "read
]the man on ...".
What do you do when you make your dvd backups? The clock should not be
doing this!
Are you actually running ntp?
You could see if it is actually true that the dvd backup is doing it by
recording
date
before the backup, and comparing it with that on another machine whose
clock keeps the time, and then doing it again afterwards.
The machine can tolerate the time being advanced in a jump but can get
very difficult if the clock jumps back (files have earlier dates than
others, duplicate times for files, etc)
- Next message: Jeroen Geilman: "Re: Samba 3 Replace Windows PDC and BCDs?"
- Previous message: Bill Unruh: "the round() functions seems to be totally broken"
- In reply to: Allan Cady: "Clock drift problems"
- Next in thread: Christopher Browne: "Re: Clock drift problems"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Relevant Pages
|
