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Re: How to Boot with LVM

Rick Thomas a écrit :
> I configure a small (<1GB) "/boot" partition as a primary partition 
> (e.g. /dev/sda1) on one of the disks, with the same space on the other 
> disk unused. [1]


> The two swap partitions I set up as a RAID0 (e.g. /dev/md0).  This will 
> be my system swap. [2]
> [1] I know there are ways to make grub work with RAID1, but it's too 
> complicated for me to get it right.

1) Set up /boot as RAID 1 (or 5, 6, 10).
2) grub install /dev/sda ; grub install /dev/sdb
How is that complicated ?

> [2] There's no particular point in putting swap on a redundant RAID.  

Yes there is : system availability. Defective swap may have the same
catastrophic effect as defective memory.
RAID is not only about data redundancy. Redundancy is used to allow the
system to tolerate a disk fault and continue to operate untill you
decide to replace the faulty disk. But maybe you don't care about your
system availability.

> If your swap develops a bad spot, you probably want to boot from a CD 
> into rescue mode ASAP so you can take necessary measures to fix the 
> problem. Using RAID1 for swap would just mask the problem - possibly
> until it's too late.

Are you serious ?
Mdadm monitoring can warn you as soon as a faulty disk is detected,
allowing you to take appropriate action while the system is still operating.
Without redundancy, a defective swap may cause the system to misbehave
or even crash at any time without any warning !

> [3] Conversely, everything else on the system wants to be redundantly 
> protected.

Why ? If you don't care about availability, just restore from the
backup. No need for RAID.

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