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Date: Sat, 26 Mar 2011 00:25:41 -0500
From: Ron Johnson <ron.l.johnson@cox.net>
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Subject: Re: [linux-lvm] Powerfailure and snapshot consistency
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On 03/25/2011 11:52 PM, Stuart D. Gathman wrote:
> On Fri, 25 Mar 2011, Ron Johnson wrote:
>
>> On 03/25/2011 11:24 PM, Stuart D. Gathman wrote:
>> [snip]
>>>
>>> 2) make sure important LVs do not span multiple PVs (except for LVM
>>> mirroring) - you could be unhappy in the event of a system crash.
>>>
>>
>> But isn't "volumes larger than physical devices" (one of) the raison
>> d'etre of LVM?
>
> Yes, but a power failure can then mess up the ordering of write completions
> distributed between 2 or more PVs, which could defeat the assumptions made
> by your file system journaling.
>

File a bug...  But against what?  LVM?  The FS?  The block layer?

> and
>
> No, YMMV, but I generally have a number of smaller LVs (for virtual
> machines)
> and it is nice to have a larger pool of PVs from which they are allocated.
>

I guess I'm just a DP Dinosaur who thinks that if a machine is beefy
enough to run a bunch of services then those services should run 
directly on the machine.  (Obviously I don't work for a web hosting 
company...)

-- 
"Neither the wisest constitution nor the wisest laws will secure
the liberty and happiness of a people whose manners are universally
corrupt."
Samuel Adams, essay in The Public Advertiser, 1749