[nflug] RAID
Corey Reichle
coreyreichle at verizon.net
Mon Feb 11 14:39:16 EST 2008
If you don't mind rebuilding it, pull a drive :)
=====================
From: Eric #4011 <eric at bootz.us>
Date: 2008/02/11 Mon PM 01:30:33 CST
To: nflug at nflug.org
Subject: Re: [nflug] RAID
Ok, my new system is in working order.
Now I want to test a hard drive failure, any thoughts on how I should
approach this?
Eric #4011 wrote:
> Ok, decided
>
> /boot RAID1 3 active and 1 spare -1GB
> /SWAP RAID1 3 active and 1 spare -2GB
> / RAID5 3 active and 1 spare -MAX
>
> then made / RAID 5 and LVM volume group
>
>
>
>
>
> Eric #4011 wrote:
>> I really like the RAID 0+1 idea but I'm not sure how to do it with
>> Linux software RAID, do I need to create two RAID 0's and then
>> combine them with a nested RAID 1 to achieve RAID 0+1. I will
>> consider RAID 5 as suggested.
>>
>>
>> Corey Reichle wrote:
>>> You need to consider this: RAID0 is the best performance wise, but
>>> at the risk of a single drive going will bring down the array.
>>>
>>> RAID1 will get you some fault tolerance, but it takes a hit since
>>> two physical writes for every logical write. The only way to
>>> circumvent much of the performance loss is separate controllers.
>>>
>>> I would suggest RAID5. Best performance gain for fault tolerance,
>>> as well as increased performance over a RAID0 with the right
>>> controllers.
>>>
>>> ====================
>>> From: Eric #4011 <eric at bootz.us>
>>> Date: 2008/02/11 Mon AM 07:01:46 CST
>>> To: nflug at nflug.org
>>> Subject: Re: [nflug] RAID
>>>
>>> Great, I'll use Raid Software then.
>>>
>>> Space isn't a problem each drive is 160GB and it's just a small
>>> email server of about 100 people, so raid 0 or 1 would be best for
>>> performance?
>>> these are also hot swap drives does a certain raid matter in this
>>> instance?
>>>
>>> Thank you,
>>> Eric
>>>
>>> Mark Musone wrote:
>>>
>>>> I'd probably use software raid over most onboard SATA raid
>>>> controllers..
>>>>
>>>> You may also want to consider raid-5, since you'll get more usable
>>>> storage
>>>> space than raid0-1
>>>>
>>>> Mark
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: nflug-bounces at nflug.org [mailto:nflug-bounces at nflug.org] On
>>>> Behalf Of
>>>> Eric #4011
>>>> Sent: Friday, February 08, 2008 3:36 PM
>>>> To: nflug at nflug.org
>>>> Subject: Re: [nflug] RAID
>>>>
>>>> Yes it does help, and I want to be sure I do this the right way.
>>>> The board is a TYAN Tomcat K8E using a Nvidia RAID controller for
>>>> SATA drives... I have heard that the onboard RAID controllers are
>>>> not that great, however which is better poison the Linux RAID
>>>> software or the onboard RAID controller?
>>>>
>>>> Rob Dege wrote:
>>>>
>>>>> It's been a while since I've spoken in RAID, but I think your
>>>>> terminology is off. RAID-0 by default requires at least two hard
>>>>> drives in order to configure. The same goes for RAID 1.
>>>>>
>>>>> So, in this instance, you will use two drives to create a RAID-0
>>>>> array. This array now appears as a single drive. You then create
>>>>> another RAID-0 array using the other two disks. This array now
>>>>> appears as a single drive. So now, you have two RAID0 arrays
>>>>> independent of each other. Finally, you create a RAID-1 mirroring
>>>>> array, using the two RAID-0 disks that you just created.
>>>>>
>>>>> Thus, you now have a single drive, with the capacity of two
>>>>> drives. If this is all handled within the RAID controller, linux
>>>>> will only acknowledge the existence of this RAID-0+1 drive as a
>>>>> single disk. So you won't be able to use the linux software RAID
>>>>> to create another layer of mirroring.
>>>>>
>>>>> Of course, this is assuming that your RAID controller is doing all
>>>>> of the array structure and work. Most of the onboard RAID
>>>>> controllers in today's motherboards, and built shoddy. Their
>>>>> contain the cheap hardware, but you need to install software to
>>>>> configure/access the onboard controller.
>>>>>
>>>>> Plus, it's been a while, but I do recall some warning about not
>>>>> putting either the root directory or the /boot directory on a
>>>>> raid. It has something to do about the module needed by the
>>>>> kernel to identify the raid drive being stored on the raid drive
>>>>> or something like that.
>>>>>
>>>>> oh well, hope this helps somewhat.
>>>>>
>>>>> -Rob
>>>>>
>>>>>
>>>>> On Feb 8, 2008 12:49 PM, Eric #4011 <eric at bootz.us
>>>>> <mailto:eric at bootz.us>> wrote:
>>>>>
>>>>> Hi, I was wondering if the following RAID configuration is
>>>>> possible?
>>>>>
>>>>>
>>>>> I have 4 SATA drives for RAID and am using MediaShield utility to
>>>>> configure a RAID 0+1
>>>>>
>>>>>
>>>> ****************************************************************************
>>>>
>>>> *******************
>>>>
>>>>> MediaShield States RAID 0+1 is:
>>>>> RAID 0 drives can be mirrored using RAID 1 techniques,
>>>>> resulting in a RAID 0+1 solution
>>>>> for improved performance plus resiliency
>>>>> The controller combines the performance of data
>>>>> striping (RAID
>>>>> 0) and the fault tolerance
>>>>> of disk mirroring (RAID 1). Data is striped across
>>>>> multiple
>>>>> drives and duplicated on
>>>>> another set of drives.
>>>>>
>>>>>
>>>> ****************************************************************************
>>>>
>>>> *******************
>>>>
>>>>> After this I have two drives and I am ready to install
>>>>> linux(debian etch)
>>>>>
>>>>> My thoughts are if I also use RAID 1 software(linux) with the
>>>>> existing
>>>>> two drives I will have one hard drive writing to three hard
>>>>> drives?
>>>>>
>>>>> I'm wondering if this is possible?
>>>>>
>>>>> Thank you in advance for your explanations
>>>>>
>>>>> Thank you,
>>>>> Eric
>>>>> _______________________________________________
>>>>> nflug mailing list
>>>>> nflug at nflug.org <mailto:nflug at nflug.org>
>>>>> http://www.nflug.org/mailman/listinfo/nflug
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> -Rob
>>>>>
>>>>> Ben Franklin Quote: "They that can give up essential liberty to
>>>>> obtain a little temporary safety deserve neither liberty nor safety."
>>>>> ------------------------------------------------------------------------
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> nflug mailing list
>>>>> nflug at nflug.org
>>>>> http://www.nflug.org/mailman/listinfo/nflug
>>>>>
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