cancel
Showing results for 
Search instead for 
Did you mean: 

RAID 5

SOLVED
Go to solution
Abdul R. Arab
Occasional Visitor

RAID 5

I have an HP ProLiant ML370 Series server with 3 72GB hard disks devided into 2 partitions C & D.
If i enter to the device manager i can see only two hard disks installed while physically i have 3.
I need an explanation to that please.

Also the RAM capacity is 4 GB. If i enter to the BIOS i can see the correct capacity of the RAM while if i right click the "My Computer" and go to properties i can see the RAM capacity is 3.25 GB
Kindly explain.

Regards,
Abdul R. Arab


9 REPLIES
Ivan Ferreira
Honored Contributor
Solution

Re: RAID 5

1- As your subject says, RAID 5 makes the 3 disks as one disk, using one of the disks as parity, so if one disk fails, data is not lost.

You see two disks in windows because you have two partitions in the RAID 5 disk.

2- You must alter the boot.ini file to include the /PAE boot option to be able to detect all memory.

If you don't plan to install linux later, you missed the forum ;)
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Court Campbell
Honored Contributor

Re: RAID 5

woo, I would never say raid 5 uses one disk for parity. the parity is distributed across the disks. If only the one disk had all the parity data you would be up a creek if you lost just that disk.
"The difference between me and you? I will read the man page." and "Respect the hat." and "You could just do a search on ITRC, you don't need to start a thread on a topic that's been answered 100 times already." Oh, and "What. no points???"
Uwe Zessin
Honored Contributor

Re: RAID 5

> If only the one disk had all the parity data you would be up a creek if you lost just that disk.

Hm. I disagee, because you still have all data on the remaining data disk drives. You are now running a RAID-0 set. Of course, it cannot withstand the loss of one more disk drive, but RAID-5 can't do that either.

What Ivan has described (multiple data disk drives with all parity stored on one disk drive) is called RAID-4. The problem with this is that it is not good for a large number of writes, because the parity disk drive is always being hit.

RAID-5 works around this by distributing the parity data across all disk drives in the RAID set.
.
Ivan Ferreira
Honored Contributor

Re: RAID 5

>>> 1- As your subject says, RAID 5 makes the 3 disks as one disk, using one of the disks as parity, so if one disk fails, data is not lost.

This was a simple explanation. If you want a more "strict" definition, consider "the space of one disk" for parity. Most people know that the RAID 5 parity is distributed.

And for strict definition, it's not a RAID 4, maybe a RAID 3.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Court Campbell
Honored Contributor

Re: RAID 5

Uwe, I agree. I wasn't thinking.

Ivan, not trying to be picky, just wanted Abdul to have a more accurate description of raid5.
"The difference between me and you? I will read the man page." and "Respect the hat." and "You could just do a search on ITRC, you don't need to start a thread on a topic that's been answered 100 times already." Oh, and "What. no points???"
Uwe Zessin
Honored Contributor

Re: RAID 5

> it's not a RAID 4, maybe a RAID 3.

Both, RAID-3 and RAID-4 use a dedicated parity disk drive, but RAID-3 uses a MUCH smaller chunk size than RAID-4 and RAID-5.
.
Abdul R. Arab
Occasional Visitor

Re: RAID 5

Thanks guys for your reply, but i still need a small help from you regarding the RAM issue.
Ivan and all, would you explain more on how to do it.

Regards,
Ivan Ferreira
Honored Contributor

Re: RAID 5

Here is a thread where explains how to do it:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1009988

Cheers.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Abdul R. Arab
Occasional Visitor

Re: RAID 5

Ivan i would rate your reply 100 instead of 10:)
Thanks alot you bailed me out of a dilemma :)