You are correct about the cacheing of filesystems. The clustered systems I referred to are DB2 Connect gateways and contain no shared filesystems. I will route all DB2C users through one gateway wile backing up the other. Then reverse positions. When both are done, bring them both online.
For systems with active filesystems, they must be shut down and a SNAP taken. They can be brought up while the SNAP volumes are copied to tape. Lea Stahr Sr. System Administrator Linux/Unix Team 630-753-5445 [EMAIL PROTECTED] -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of J Leslie Turriff Sent: Friday, July 28, 2006 11:04 AM To: [email protected] Subject: Re: Bad Linux backups Well, I can see that clustering is a solution to the availability of a service while a host is shut down, but I don't see how it makes thinks any better in regards to backing up the filesystems used by the cluster. As long as any of the hosts in the cluster is using a filesystem in R/W mode there are going to be pieces of data cached in main memory that the filesystem doesn't know about, and that means that snapshots, etc. done from outside will not be valid. Seems like the base issue is that Linux doesn't do write-through cacheing, so the filesystem will almost never be valid to an outside observer (see also Schroedinger's cat). J. Leslie Turriff VM Systems Programmer Central Missouri State University Room 400 Ward Edwards Building Warrensburg MO 64093 660-543-4285 660-580-0523 [EMAIL PROTECTED] >>>[EMAIL PROTECTED] 07/28/06 10:31 am >>> >From what I've seen, a lot of that information is usually kept in the user's browser via cookies or "session cookies." For things that aren't, mirroring the data on separate physical devices, on separate controllers, etc., etc., provides the redundancy needed. The whole point of clustering is not to have _any_ single points of failure. That's why clustering an application is _at least_ two times more expensive than not clustering it. Mark Post -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of John Summerfied Sent: Thursday, July 27, 2006 8:37 PM To: [email protected] Subject: Re: Bad Linux backups David Boyes wrote: >I think Lea means: > >For cluster takeover to work seamlessly, your application has to keep >session data in some common location between the servers. There's the point that has me: how do you backup that location? Is it something that, if it fails, you quickly find a new one and tell the PC buyer you had a "technical problem" and would they mind starting again? -- Cheers John ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 !DSPAM:32225,44ca2f9e88571098210962! ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
