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General RAID questions (RAID 1)

 
RickTw
Occasional Advisor

General RAID questions (RAID 1)

Hi,
I have a couple general RAID questions about my ML110G5 (I'm using RAID 1)

1) Which disk is used when reading from the array? Does the controller alternate between disks to share the 'wear and tear'?

2) I understand that the 2 disks are mirrored and therefore should be identical. But is there a way for me to 'verify' this?
I have heard that sometimes the disks won't be 100% mirrored - resulting in problems when rebuilding the array from the surviving disk.

Thanks!
7 REPLIES
marcus1234
Honored Contributor

Re: General RAID questions (RAID 1)



Hi Rick the controller alternates between disk for speed ,so wear and tear is even..

Rick when using a mirror use same model disk same speed, preffered same firmware etc,

now if one fails another like disk will rebuild,


only time it will not rebuild is if one disk fails , and then it is not changed (apart from failing controllers etc)immediately , and second disk start to fail , now inserting a new disk it can only get a mirror of what is left ,

for a mirror to work a good working disk is required ,
from this page get the ACU tool
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareIndex.jsp?lang=en&cc=us&prodNameId=3577715&prodTypeId=15351&prodSeriesId=357770

use this tool to verify all is okay it is the offical HP tool and designed for this purpose , when ever running this tool open a search box ctrl f and look for hard write errors that is the best clue adisk is on the way out , also under model you can see firmware etc,
it will show predictive failtures long before they occur..I find it quite reliable.

.
Enjoy..

This is how we thank in the forum

http://forums11.itrc.hp.com/service/forums/helptips.do?#33



RickTw
Occasional Advisor

Re: General RAID questions (RAID 1)

The link for the tool returns a 'page not found' message.

You said that I should use "same model disk and same speed".

I currently have identical disks for the array. But, what happens if a disk fails in a couple of years and the manufacturer doesn't make that disk model anymore?

marcus1234
Honored Contributor

Re: General RAID questions (RAID 1)

hmm , working link

http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=15351&prodSeriesId=3577708&prodNameId=3577715&swEnvOID=1005&swLang=8&mode=2&taskId=135&swItem=MTX-f0790470403f4da3bd94126308

when a disk like these is not produced anymore , a similar compatible disk designed to be compatible is out for around 5 years on average if not longer..

hope this helps
marcus1234
Honored Contributor

Re: General RAID questions (RAID 1)

In windows you can just run acu array config utility shows disk status info etc..
RickTw
Occasional Advisor

Re: General RAID questions (RAID 1)

How will I know if a replacement disk is compatible?

I have read that replacement disks don't need to be 'exactly' the same size. Will I need to know the number of disk-heads and disk-platters, etc

I would imagine it be advisable to go with the same manufacturer, i.e Seagate.
Jimmy Vance
HPE Pro

Re: General RAID questions (RAID 1)

Mark is partially correct on disk access. The disks do not alternate, but read commands can be seperately spread across both disks. Write commands only write data to the primary disk, which at some point the data is copied to the mirror drive. So it is true that there is a very small window where the diks are not actually 100% mirrored

The Array Configuration Utility (ACU) will not work on a ML110 G5 as the embedded SATA RAID controller is not an HP Smart Array controller.

If your using Windows, this is the tool to manage the embedded SATA controller

HP Embedded G5 SATA RAID Controller Manager for Windows Server 2003/2008

http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=15351&prodSeriesId=3577708&prodNameId=3577715&swEnvOID=1005&swLang=8&mode=2&taskId=135&swItem=MTX-3f27718395524ff393ffc94d2d



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marcus1234
Honored Contributor

Re: General RAID questions (RAID 1)

thanks jimmy

i posted wrong link for smart controller , instead of sata offline diagnostics which are required here

Rick only HP disks are supported although HP does not manufacture the disks the firmware on them is at times tailored for HP sysboards and controllers too..
:)