Re: RAID 1 versus RAID 5

From: SuperGumby [SBS MVP] (not_at_your.nellie)
Date: 12/02/04 

Date: Thu, 2 Dec 2004 22:27:56 +1100

What you have to keep in mind Kev is that articles which suggest your
root/boot partitions cannot be _software_ RAID5 are correct.

The RAID array must be available to the boot process. If it's _hardware_
RAID5 you're OK.

"Kevin Weilbacher [SBS-MVP]" <kweilbacMVP@gte.net> wrote in message
news:et6g0%23F2EHA.936@TK2MSFTNGP12.phx.gbl...
> Reply to Fred -
> your points are well taken and should be considered. I was simply
> addressing the fact that posts and articles that say that you CANNOT have
> your system partition on a Raid-5 disk are incorrect.
>
> --
> Kevin Weilbacher [SBS-MVP]
> "The days pass by so quickly now, the nights are seldom long"
>
>
> "Fred Blum" <h.f.blum@marketconnectnospam.nl> wrote in message
> news:%23T4XKiE2EHA.1192@tk2msftngp13.phx.gbl...
>>
>> Thanks,
>>
>> had not thought of that and you're right. My RIAD controller doesn't
>> allow a dynamic resizing on W2K.
>> IMHO opinion this thread question/answer should be in the FAQ.
>>
>> Fred
>>
>> "Joshua Bolton" <JoshuaBolton@discussions.microsoft.com> wrote in message
>> news:5AC99C16-73A5-4B52-98B6-113D9E26E73D@microsoft.com...
>>> Kevin I would point out that this configuration precludes any disk space
>>> being added to your system. This is why the standard has been mirror
>>> [raid1]
>>> the OS and stripe [raid 5/0+1/10] the data.
>>>
>>> Here is the reason why. It is common to need to add disk space to the
>>> data
>>> partition/drive. Most raid controllers don't allow dynamic upgrades in
>>> the
>>> raid array. So to add more disk space with your present configuration
>>> you
>>> have to wipe the existing array and recreate the raid5 array with the
>>> additional disk so you have more space. This usually means you have to
>>> repartition the way you want, reinstall the OS and backup software and
>>> restore from a backup. A long painful process.
>>>
>>> Lets say you have a raid controller that can add the disk to the array
>>> dynamicly. Great. Now you have system, apps and data partitions. How
>>> are
>>> you going to add the "unallocated space" to the data partition? You
>>> only
>>> have two options. The best being buy a server version of Partition
>>> Magic and
>>> use it to add the space to data. Or create a volume set between the
>>> data
>>> partition and the unallocated space [very bad choice since I have seen
>>> chkdsk
>>> /f destroy a volume set].
>>>
>>> Now if you had mirrored the OS and stripped the data [in your case apps
>>> and
>>> data] it is a simple matter of backup apps and data, reinit the array
>>> with
>>> the added disk, use disk manager to partition as you desire and format
>>> the
>>> partitions. Then restore from backup. I have done this in 4 hours on a
>>> Sat.
>>> [depending on how long it took to init the array and restore data].
>>>
>>> Lets say you wanted to make the OS drive space larger. You can't mirror
>>> to
>>> a larger drive. But you can break the mirror, use ghost to ghost from
>>> small
>>> driver to larger and then with another larger drive in the system mirror
>>> the
>>> two. Again a fairly straight forward operation which you can not do if
>>> you
>>> have all three partitions on a single raid5 array. This is a two hour
>>> or
>>> less operation.
>>>
>>> Just something to think about.
>>>
>>>
>>>
>>> "Kevin Weilbacher" wrote:
>>>
>>>> Fred, I know way back when it was recommended not to use raid-5 for
>>>> your
>>>> system partition. But I don't believe that is applicable any longer. I
>>>> know
>>>> I use hardware Raid-5 for all my SBS servers without any problems. I
>>>> take my
>>>> 3 or 4 drives, set them up in Raid-5, and partition them into 3
>>>> sections:
>>>> system, apps, data.
>>>
>>
>>
>
>