LinuxQuestions.org
Welcome to the most active Linux Forum on the web.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Newbie
User Name
Password
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!

Notices


Reply
  Search this Thread
Old 02-01-2012, 05:54 PM   #1
dvah
LQ Newbie
 
Registered: Jan 2012
Posts: 13

Rep: Reputation: Disabled
Setting RAID5, few unclear details


I just installed UBUNTU (I am new to UBUNTU & linux) on a 40GB SATA - sdd, I have additional 3 SATA drives 1.5 TB each = sda, sdb,sdc and I want to set LVM over RAID 5, I intend to assign the whole drive for the RAID.
1. Do I need to partition the drives for setting the RAID or I can go ahead and set the RAID5 over the whole drive devices without setting any partitions, from my search I understand that both is possible but not clear on which is better and why?
2. Assuming the above is that I need or should partition. Which command is the best for using script to do the partitioning: "parted" or "sfdisk" (or other command...)
3. What should be the partition type FD or DA or other type?
4. If I am using "parted" command to do the partitioning how do I set the type to FD or DA etc using parted or I must use sfdisk for doing RAID and LVM?
5. I understand that sfdisk can't handle large drives, can I still use it and set on each of my drives multiple / smaller partitions each can be created by sfdisk and create multiple RAID5 arrays based on the partitions and than assign all the RAIDs to the LVM so the LVM still see the whole storage? Does this extra partitioning and RAIDs affect performance?
6. What performance can I expect from LVM over RAID 5 if my system is ASUS E35M1 motherboard with AMD E350 Dual Core CPU and 4GB RAM SATA 3G drives for the RAID/LVM and SATA 1.5G for the system drive?
 
Old 02-01-2012, 06:54 PM   #2
chrism01
LQ Guru
 
Registered: Aug 2004
Location: Sydney
Distribution: Centos 6.9, Centos 7.3
Posts: 17,411

Rep: Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397
Do wait for other people's comments, but

1. best practice is to create a partition across each disk

2. don't know about 'best', personally I've always used fdisk.; YMMV

3. RAID uses type fd

Note:
generally, 3 drives is min for RAID5, but this would mean that when a disk goes bad you'll need a backup system.
You may(!) be able to recover from 2, but I wouldn't bet on it.
You can add an extra drive as hot standby.

https://en.wikipedia.org/wiki/Standard_RAID_levels
https://en.wikipedia.org/wiki/RAID

HTH
 
Old 02-01-2012, 06:57 PM   #3
suicidaleggroll
LQ Guru
 
Registered: Nov 2010
Location: Colorado
Distribution: OpenSUSE, CentOS
Posts: 5,552

Rep: Reputation: 2112Reputation: 2112Reputation: 2112Reputation: 2112Reputation: 2112Reputation: 2112Reputation: 2112Reputation: 2112Reputation: 2112Reputation: 2112Reputation: 2112
Quote:
Originally Posted by chrism01 View Post
Note:
generally, 3 drives is min for RAID5, but this would mean that when a disk goes bad you'll need a backup system.
You may(!) be able to recover from 2, but I wouldn't bet on it.
You can add an extra drive as hot standby.
RAID5 always has one drive of redundancy. It doesn't matter how many drives you have in your array, you can always lose one without losing any data and rebuild from the rest of them with RAID5. If the entire array crashed after losing a single drive, that would be RAID0 (aka zero redundancy, an accident waiting to happen).

Last edited by suicidaleggroll; 02-01-2012 at 06:59 PM.
 
Old 02-01-2012, 07:35 PM   #4
dvah
LQ Newbie
 
Registered: Jan 2012
Posts: 13

Original Poster
Rep: Reputation: Disabled
Chris,
Thanks for the details.

The reason for my question about FD or DA type is the following comment I found on other thread-

"(From the mdadm 2.6.8 man-page) When creating partition-based arrays using mdadm and version-1.x superblocks, the partition type should be set to 0xDA (non fs-data). This type selection allows for greater precision since using any other type [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], might create problems in the event of array recovery through a live cdrom."

any idea about this array recovery problem when using FD type, I guess what is being suggested is that during the recovery process the system trys to find file system on each of the RAID drives if they are set as FD while if they are set as DA it does not and manage to move forward?

Thanks

Dov
 
Old 02-01-2012, 07:48 PM   #5
chrism01
LQ Guru
 
Registered: Aug 2004
Location: Sydney
Distribution: Centos 6.9, Centos 7.3
Posts: 17,411

Rep: Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397Reputation: 2397
First time I've heard of that; all the references say DA = 'non-FS data' & FD = linux raid auto.
I guess I'd check that you do have that version of mdadm & 1.x superblocks...

Let us know how that goes
 
Old 02-01-2012, 08:11 PM   #6
dvah
LQ Newbie
 
Registered: Jan 2012
Posts: 13

Original Poster
Rep: Reputation: Disabled
It does not define any version for the mdadm and regarding to the superblock, I have no idea what is the version, actually I don't have any version of superblock yet since I din't start creating the partitions...
It is a lengthy process, I prefare to do it right with the help of people like you that have experience with UBUNTU/linux.

Any Idea what performance can I expect from software RAID 5 on my system? or otherwise on systems that you had experience with?

Thanks
Dov
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
Recreate a Raid5 MD0 into a Raid5 MD3 CADIT Linux - Server 2 01-11-2010 05:46 AM
Multi Layer RAID50 fail (Intel SRCS14L RAID5 + 3ware 9550SX-4LP RAID5)+Linux RAID 0 BaronVonChickenPants Linux - Server 4 09-27-2009 05:06 AM
Trouble setting up RAID5 cammac725 Red Hat 2 05-11-2006 01:08 PM
Setting up and configuring Wine, Details needed. Poneyboy Linux - Software 1 05-06-2006 11:53 PM
Setting up Passwd expiration details deepika Linux - Newbie 1 07-17-2003 05:28 PM

LinuxQuestions.org > Forums > Linux Forums > Linux - Newbie

All times are GMT -5. The time now is 07:48 AM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration