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Re: LVM root?

dtutty@porchlight.ca writes:

> I am lucky in that my backup-set size is small; Its been tight on a 100
> MB Zip disk and absolutley essential stuff (stuff I need to be able to
> access absolultly from anywhere, any time) fits on one floppy in gzipped
> plain-text.  My approach for the new root drive was to buy the most
> reliable drive I could.  If it dies, get a new drive and reinstall,
> restore from backup and carry on.  
> Your approach using Raid may be overkill for me, I don't know.  

If you have 2 disks (and you said you would have anyway) there really
is no reason not to use raid.

If you have 2 disks for the extra size you don't want to use raid1 for
the main data though. Keep it to the essentials. So you give up say
10G of each disk for raid1 for the essential stuff and then raid0 for
the rest for the video data. On a (single) disk failure you would
loose your video data but not your system. Pop in a new disk, restore
the video data and just keep going.

It takes only a few minutes to think this through and then select it
in Debian-Installer but when a disk fails it saves you hours of
reinstalling. You give up 10G space for future hours of work. I find
that always worth it.

[Raid is no replacement for a real backup though.]

> The board itself has hardware SATA raid available.  If I go for raid,
> then I'll ask here for the advantages/disadvantages.

I doubt that. All the desktop boards with onboard raid have only
softraid. They can boot from the raid but it is just software support
in the bios and windows/linux has to have its own driver for it. The
proper linux software raid is better than emulating the bios software
so that is preferable.

> More to the point for me, though, is where can I get current howtos or
> guides on fixing problems when things are in raid or LVM?  Its a whole
> new world for me and the LDP HOWTOs are too out of date, and
> debian-reference doesn't cover it.  
> At this point I'm leaning to the single disk, regular / at 512 MB (/tmp
> is separate LV) and the rest PV.
> Since my / doesn't change much, when I add a second disk, just copy /
> and have a non-raid copy available to boot into.  When I do make
> changes, just copy it over; could even make it part of the regular
> backup strategy.  
> Thanks for the ideas,

You could also setup / as degraded raid1. That means you set it up
with one disk there and one missing. When you get your second disk you
just add it with "mdadm --add /dev/md0 /dev/sdb1" and a few minutes
later the raid1 will be fully up.

Does anyone know if the D-I supports this from the menues?

> Doug.


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