Re: Wheezy install - grub wont write to MBR with RAID and LVM
On Fri, 08 Jul 2011 06:33:50 -0400, Tom H wrote:
> On Thu, Jul 7, 2011 at 10:37 AM, Camaleón <noelamac@gmail.com> wrote:
(...)
>>>> I don't fear dmarid but manufacturer's BIOSes that can make use non-
>>>> standard ways of handling hard disk controller data. You know, they
>>>> don't provide open specs for devels can develop stable tools, so I
>>>> would prefer to stick to mdraid and AHCI or SATA mode that are
>>>> well-known. I don't like to play "russian roulette" with my data.
>>>
>>> To Cameleon: You cold say that of "real" hardware raid too! I *much*
>>> prefer mdraid but the fears about fakeraid and "real" hardware raid
>>> are overblown.
>>
>> (...)
>>
>> Most of the real hardware raid controller manufacturers (i.e., adaptec,
>> areca, 3ware...) develop their drivers in collaboration with kernel
>> developers so, nope, not the same thing at all :-)
>
> Do you have any basis upon which to cast doubt on the development of
> FakeRAID drivers?
Should you have read my post you had noted that I did not say nothing
against dmraid but BIOS manufacturers.
Can you please point me to any BIOS that is open?
Can you please point me to any BIOS manufacturer that is actively
collaborating with dmraid devels?
Can you please tell me why there are drivers for this fake raid
controllers for Windows and not for linux?
We all know that dmraid is an effort that comes from only one side (open
source devels) and not from motherboard's makers. If you like to put your
data on unknown hands that's up to you. All the docs I've read from
kernel guys state it very clear: if you want to setup a RAID facility,
avoid fake raid controllers as much as you can. They suffer not only
from performance issues but are less reliable.
> Anyway, this wasn't the issue that I've seen raised.
>
> The argument that I've seen (and I've fallen vistim of this because a
> purchasing manager once dropped a letter from the end of a RAID card
> model) is "can you be sure if a RAID card or a motherboard is replaced
> that you'll be able to plug in your disks and boot without a hitch?" I
> prefer mdadm, whether this is an issue or not.
Yes, but that's another -and complete- different problem.
Only linux software raid (md) allows you to easily migrate a raid without
many troubles.
Most of the hardware based RAID cards also suffer from this (although
manufacturers are adding the option for an easy migration to another
controller of the same brand, that's still not the common rule). But
everybody should now what are the advantages of a true hardwrae RAID card.
And lastly, fake-raid cards suffer not only for the worst performance but
also from having to deal with a motherboard change.
So in brief, when thinking in RAID I first try to choose a real hardware
raid controller, second option would go for linux softare raid (md) and
lastly, fake-raid (dm) is there is no other chance...
Greetings,
--
Camaleón
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