Hot swapping RAID 5

[Nicholas Hildreth]

We have a ML350 G5 with the standard raid setup of RAID 1 (2x36GB disks) and RAID 5 (4x146GB disks). The computer has 8 slots, so currently only 6 are used. All are SAS and hot swappable.

My question is, if a disk is removed from one slot and put back into a 'different' slot, what will happen? Will it identify the disk with the information that's currently on it and continue as normal, or will it completely rebuild the disk?

[KarloChacon · Accepted solution]

hi

yes you can do it no problem at all
the controller is going to detect a new ID for the HDD and report that nothing else
and also because the RAID level is kept in the HDD RIS tables the HDD is going to be detected again in the current RAID LEVEL


regards

[Nicholas Hildreth]

Thanks for that. The reason I asked was because I noticed that the 6 hard disks in this machine had been inserted 'in order' into the 8 slots. This means that the two disks making up the raid 1 array AND two of the disks make up the raid 5 array were assigned PORT 1. While the remaining two disks of the raid 5 array were assigned PORT 2. Assuming that there are four slots to a port, I wanted to relocated the raid 5 array such that they were all located on PORT 2 and not split down the middle. Although I'm not sure this will gain me anything.

Regards,
Nicholas.

[KarloChacon]

hi

if you want to allocate just 1 HDD you can do it online

but if you want to allocate more than one power off you server and do it

regards

[James ~ Happy Dude]

Hello Nicholas,

I think you are referring to the "Drive Roaming" Concept.

HP Smart Array controllers support drive roaming, which allows administrators to move hard drives and arrays while maintaining data availability. Drive roaming allows administrators to move one or more hard drives that are members of a configured logical drive to a different bay position as long as the new bay position is accessible by the same controller. In addition, it allows administrators to move a complete array from one controller to another, even if controllers are in different servers. Such cases, there is no "REBUILD".

Hence, the Keyword for moving one HDD to a Different BAy is, the new bay/slot is being ACCESSED by the "SAME CONTROLLER".

If its accessed by a different controller, then a REBUILD is 100% sure.. resulting in POTENTIAL DATA LOSS.


Regards,
James.

[James ~ Happy Dude]

As i read, the HDD being inserted "in order" .. It doesnt matter where the HDD are placed in the Bays... as long as You can identify them to its respective Raids.

Yes, Arranging them into sections are easier for us to identify ... instantly !

Regards,
James.

[James ~ Happy Dude]

Yet again,

Karlo, Even if there is more than one HDD which has to change bays, I dont think the server has to go OFFLINE; Since, assuming, these HDD are for the same controller, there are no REBUILDS! so, swap HDD, wait until its acknowledged & go for the Other HDDs;

:)

Regards,
James.

[KarloChacon]

yes

"Drive Roaming" that is the concept behind that thanks James

that applies to different for the same controller or even you can take those HDDs to another server with an identical controller or compatible

see this link
you'll see a chart which points out compatibility between
» SA-P400

» SA-P600

» SA-6402

» SA-642

http://urlao.com/sa


-------------
yes James I was thinking about that but just in case I was thinking is safer

[Jimmy Vance]

While the system is up and running, if you pull a drive the controller will see this as a failure. When you plug the drive back in, it will have to be in the same slot and a rebuild will take place.

If you want to move the drives around to different bays, as stated this can be done, but you need to do it while the system is powered down. When you boot back up the controller will see the drive order has changed and update accordingly