Sponsored Content
Full Discussion: RAID5 + STRIPED LUNs
Special Forums Hardware RAID5 + STRIPED LUNs Post 302773079 by hicksd8 on Wednesday 27th of February 2013 09:38:58 AM
Old 02-27-2013
I assume by striped LUN's you mean software RAID.
Software RAID is "poor man's RAID".

I assume that you have a hardware RAID5 controller.

There is little point in using both at the same time. Software RAID uses CPU cycles which can be bad on a system loaded with apps.

Originally there was RAID3. This striped the data over a number of drives and also had a dedicated parity drive. This meant that every file write involved a write to the parity drive hence creating a bottleneck. So RAID5 was created.

RAID5 is striped data with rotating parity. The parity function is rotated between all the drives eliminating the bottleneck. I/O is spread across a number of actuators (drives) so the more drives in the RAID5 the greater the I/O bandwidth available. Compounding this functionality with software RAID is pointless. The hardware RAID5 controller will offload all I/O processing (parity calculation) from the main CPU of the box.

Dunno whether that answers you question(s) or not? Post back any further questions if not.

So RAID5 if good for general random I/O (mixed and unpredictable read/write)
In a situation where I/O's are predominantly read-only (eg, large Oracle database with mainly read enquiries) then RAID3 will be a bit faster because there's no need to read the parity if drives are healthy.
 

10 More Discussions You Might Find Interesting

1. Programming

Finding out if a file has been striped or not

Is there a way in c to find out if a binary program contains debug information? I have tried to compare the striped and unstriped versions of two programs, but i have had a hard time understand them. (2 Replies)
Discussion started by: shienarier
2 Replies

2. SCO

Raid5 Failure

Forgive me, I do not know much about RAID so I'm going to be as detailed as possible. This morning, our server's alarm was going. I found that one of our drives have failed. (we have 3) It is an Adaptec ATA RAID 2400A controller I'm purchasing a new SCSI drive today. My questions: ... (2 Replies)
Discussion started by: gseyforth
2 Replies

3. Solaris

RAID5 problems on solaris

I have one volume raid5 with 3 slice one of them is maintenance state. I replace this slice and resync the volume. when I try to mount the file system another slice goes to last erred. Again resync and the state goes to OK but the slice in mantenance persist. I try to enabled this but persist in... (2 Replies)
Discussion started by: usdsia
2 Replies

4. Solaris

How to add disk into Striped Volume VxVM

VxVM: How to add one more disk into v08 the stripe should change from 7/128 to 8/128 v v08 - ENABLED ACTIVE 8954292224 SELECT v08-01 fsgen pl v08-01 v08 ENABLED ACTIVE 8954292480 STRIPE 7/128 RW sd bkpdg35-01 v08-01 bkpdg35 17216 ... (0 Replies)
Discussion started by: geoffry
0 Replies

5. AIX

how to mirror raid5

Hi, I have an ssa filesystem to move to san. We don't want any downtime. I heard that you can do a mirroring of existing file system on the san. The file system is a type of either raid 0, raid 1, or raid 5. Anyone know how to do this? Thanks in advance, itik (4 Replies)
Discussion started by: itik
4 Replies

6. AIX

AIX striped LV - lslv stripe width has wrong value

Hello all. I have a volume group with 8 PV's, and a logical volume striped across these 8 volumes. However, an lslv is showing: STRIPE WIDTH: 9 STRIPE SIZE: 64k There's really only eight disks, so how can the stripe width be 9? ODM also showed this: # odmget CuAt |... (4 Replies)
Discussion started by: Scott
4 Replies

7. AIX

Striped FS , need to add new disks

Hi, I have a filesystem that is created on a VG with 12 disks. The FS is striped on these disks. Now I have to add 10 more disks to this volume group to help increase the space of the same FS that is striped. How should I add these disks to the Vg and i need these disks to be added such the FS... (1 Reply)
Discussion started by: aixromeo
1 Replies

8. UNIX for Advanced & Expert Users

RAID5 multi disk failure

Hi there, Don't know if my title is relevant but I'm dealing with dangerous materials that I don't really know and I'm very afraid to mess anything up. I have a Debian 5.0.4 server with 4 x 1TB hard drives. I have the following mdstat Personalities : md1 : active raid1 sda1 sdd1... (3 Replies)
Discussion started by: chebarbudo
3 Replies

9. SuSE

Raid5

Hi all, I am currently using opensuse 12.1, We have Raid 5 array of 8 disks. A friend of mine accidently removed a drive & place it back and also added a new disk to it(making it 9 disks). now the output of mdadm --detail is as shown below si64:/dev # mdadm --detail /dev/md3 /dev/md3:... (1 Reply)
Discussion started by: patilrajashekar
1 Replies

10. Red Hat

Install RHEL6 on x3650M4 with RAID5

Hi All, I have a new x3650 M4 server with hardware RAID 5 configured 4 x 300 GB (HDD). The Raid controller is ServeRAID M5110e. Im getting "device not found" error during hardisk detection of RHEL6 install using DVD. Some pages over the net pointed to using ServerGuide media for... (1 Reply)
Discussion started by: Solaris_Begin
1 Replies
RAIDFILE-CONFIG(8)						    Box Backup							RAIDFILE-CONFIG(8)

NAME
raidfile-config - Configure Box Backup's RAID files SYNOPSIS
raidfile-config config-dir blocksize dir1 [dir2 [dir3]] DESCRIPTION
raidfile-config creates a raidfile.conf file for Box Backup. This file holds information about the directories used to store backups in. Box Backup supports userland RAID, in a restricted RAID5 configuration, where 3 and only 3 'drives' are supported. You can read more about RAID5 (and other RAID-levels) here[1]. Parameters The parameters are as follows: config-dir The directory path where configuration files are located. Usually this is /etc/box. raidfile.conf will be written in this directory. blocksize The block size used for file storage in the system, in bytes. Using a multiple of the file system block size is a good strategy. Depending on the size of the files you will be backing up, this multiple varies. Of course it also depends on the native block size of your file system. dir1 The first directory in the built-in RAID array. dir2 The second directory in the built-in RAID array. If you are not using the built-in RAID functionality, this field should be ignored. You should not use the built-in RAID if you have a hardware RAID solution or if you're using another type of software RAID (like md on Linux). dir3 The third directory in the built-in RAID array. The same notes that apply to dir2 also apply to dir3. Note that there are currently no way to add multiple disk sets to the raidfile.conf file using command line tools, etc. See raidfile.conf(5) for details on adding more disks. BUGS
If you find a bug in Box Backup, and you want to let us know about it, join the mailing list[2], and send a description of the problem there. To report a bug, give us at least the following information: o The version of Box Backup you are running o The platform you are running on (hardware and OS), for both client and server. o If possible attach your config files (bbstored.conf, bbackupd.conf) to the bug report. o Also attach any log file output that helps shed light on the problem you are seeing. o And last but certainly not least, a description of what you are seeing, in as much detail as possible. FILES
raidfile-config generates the raidfile.conf(5) file. SEE ALSO
bbstored-config(8), bbstored.conf(5), raidfile.conf(5) AUTHORS
Ben Summers Per Thomsen James O'Gorman NOTES
1. here http://en.wikipedia.org/wiki/Redundant_array_of_independent_disks#RAID_5 2. mailing list http://lists.warhead.org.uk/mailman/listinfo/boxbackup Box Backup 0.11 10/28/2011 RAIDFILE-CONFIG(8)
All times are GMT -4. The time now is 03:55 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy