[Tfug] raid help

[Brian Murphy]

Jumbled RAM is a game over situation.  Especially if the system writes a
portion of the jumble out to your disk.  Mirroring just ensures that
both drives get the jumbled data. :)

Backups are a good idea and about your only recovery option if you write
garbage data over the good stuff.

HA is good, but you typically have shared disk between the 2 servers.
If server 1 writes bad data, server 2 will be equally hosed if they
share disks.  The same is true if you have subtle file corruption and a
periodic sync between your two servers. (e.g. rsync from cron)  Keep
tape backups for anything you really don't want to lose.  Snapshots can
also be part of a good recovery strategy as long as you don't have
controller issues that scramble your entire disk.

Brian


Quoting Ronald Sutherland <ronald.sutherland at gmail.com>:
> Last time I was trying to figure out what all I should mirror I was having
> over heating issues (it was jumbling my RAM). I've also seen power line
> sags/spikes/noise, and power supply's go bad and jumble RAM. So for my needs
> I've decided that first I want data (SQL, FileServer, SVN/CVS...) mirrored
> and second my system to be fully duplicated and/or real easy to build again
> (a setup that is scripted). Having seen memory get messed up for various
> reasons, I didn't see much advantage in adding redundancy to the virtual
> part of the memory system, although I guess mirroring gives a speed
> advantage during reading. I have the hardware but not yet the time to setup
> full redundancy. Many of the Linux rags have ran articles on a service
> called "heartbeat" that allows the backup to have a clue if the main/master
> is alive and then take over if not, anyway thats what I'm looking into.
>
> http://www.linux-ha.org/Heartbeat
>
> On Sun, Mar 30, 2008 at 11:53 AM, Ryan Cresawn <jrcresawn at gmail.com> wrote:
>
>> On Sun, Mar 30, 2008 at 10:34 AM, Harry McGregor <micros at osef.org> wrote:
>> > Ronald Sutherland wrote:
>> >  > Why put a swap file on a raid drive?
>> >  Do you really want your system to crash because your swap was on a
>> drive
>> >  that failed?
>>
>> I agree.  If swap space is in use and the disk holding it dies isn't
>> it true that the system would no longer have access to some of the
>> data which should be returned to memory at some point?  The risk of
>> this occurring is greatly reduced with swap on mirrored disks.  If I'm
>> wrong I'd like to know it and why because I too have fully mirrored
>> boot disks that include '/' and swap.
>>
>> Ryan
>>
>>




The opinions or statements expressed herein are my own and should not be
taken as a position, opinion, or endorsement of the University of
Arizona.