PE 4300 Hot Swap

Yes, you can set each drive up as a single-drive RAID 0, so you can utilize each drive individually.  That way, if you do remove a drive, it will only affect that drive's array.  The drives, if set up in individual RAID 0's, could be any size.  The drive size only matters if you are configuring an array with more than one disk, wherein the array will only utilize the space per drive of the smallest drive in the array.

Hot-swap is independent of the OS, but if you are hot-swapping storage drives keep in mind there may be OS issues if you have files in use (for example) when you remove the drive.

Thank you for your response.  It's nice to know that my theory was right about the single drive RAID 0's.  Now if I removed a 36gb that was set up in this configuration and put an 18gb drive into the bay, would that work since the array was setup with the 36 gb drive?

Also, what software utility do I need to download to be able to hot-swap?

Let's say you have 4 individual 36GB disks - each in a RAID 0.  If you remove one of the 36GB drives, then its data will no longer be available.  If you put an 18GB drive in its place, then you will need to set up a RAID 0 for that drive.  If you have already done that, then the data you put on it should become available at that point.  The thing about hot-swapping in this kind of scenario, is that Windows may need to reboot (or mount the drive manually, if possible) before it can mount the drive for use.  You'd have to test that.

Hot-swap is a HARDWARE feature, not SOFTWARE, so there is no software you can load to support it - it is supported or not supported by the system's backplane.

Thank you theflash1932!  I think I'm following this.  So if I made each 36Gb drive into a RAID 0, then swapped the 36's for the 18's and made each of those drives into a RAID 0, then would each drive have an independent RAID 0 ID specific to that drive?  So like a 36Gb drive was assigned A0-2 then if I plugged it into any other slot would it have the A0-2 ID?

I found this video on YouTube http://www.youtube.com/watch?v=MRgUgHUSVtI

The guy uses this little software program to take the drive offline and back on again.  I think he said it was Dell's OpenManage but I'm not sure.  That's why I thought the Hot Swap had a software program as well as being a hardware feature.

On a side note, if I could get a 73Gb Drive working on my system I wouldn't even worry about trying to setup hot swapping.  The ones I tried were the same type of IBM that the 36Gb drives I'm running are.  When I put them in they showed up as 4.5Gb drives.  If anyone knows how to get the larger drive working I'd love to hear it.

Ok ... I see what you are talking about with "software" ... OMSA is used primarily for monitoring/managing arrays from within Windows.  Hot-swap is a hardware feature, but Dell servers have software to help you manage the arrays that are setup on the server.  In some cases, forcing a drive offline/online is necessary - usually in a recovery situation - but keep in mind, your use of the hot-swap technology-is not what hot-swap was designed for, so there are no "best practices" for your setup. 

On the 73GB drive, you might update the RAID controller (after updating BIOS and ESM).  The manual shows it originally supported up to 18GB drives, so it  may require a later version to properly support drives over that size.

I got a chance to work on the server this weekend.  First off I made to firmware floppy disk for the PERC 2/SC and it turns out that the firmware was already the latest edition.  Looks like I'll be limited to 36Gb drives on this card.

Second, I got the PERC controller program installed.  It's not as pretty looking as the one in the video but it does the same function.  I took the A0-2 drive offline and a message popped up telling me the drive and array had gone offline.  Now when I took it offline it still showed the drive was 36gb on the PERC and in my computer it was still showing a 36gb drive but just couldn't get properties for it.

I'm guessing that means that even though it's a single drive array, it expects the same size to be put back in the slot.  I'm guessing this means if I want to swap the 18gb drives around I'll have to insert one while the server is off and configure the RAID for the drive.  I guess I'll experiment with that this weekend.

Yes, it will always be looking for the drive so it can resolve its internal RAID information, but you need to tell the controller to forget about the old disk, and import the config of the new one.  Realize that, as this is out of the normal use for these servers/RAID controllers, I'm guessing at what might work, but if you put the new drive in, and do a Rescan from the OpenManage software then Force Online the drive.  (Of course, you would never do this in other than a RAID 0.)

The Rescan is an actual command on the controller or a connector.  Just go to Storage>PERC 2/SC>Information/Configuration (link at the top of the page)>then Rescan from the dropdown menu of available tasks for the controller.  If you are using the older Array Manager, you should be able to right-click the PERC and have Rescan as an option.

Yeah, RAID 1 and 5 arrays would need the time to rebuild in order not to have corruption from a read/write issue where the RAID 0 has all of the information.  I know the PERC controller I was using would rescan the channel.

I would take the drive offline--get the disk and array failure notice.  Hit the prepare removal option and once powered down the controller would rescan the channel.  When I put a drive back in it would get power, spin up, and the controller would rescan the channel.  Then to finish it was just force the drive online which wasn't an issue in this case.

I'm guessing the rescan you are referring to is the one where the drive gets put back in.

That's what I was afraid of ... that you'd have to reboot to use it.

I wish it had worked like you had hoped, but unfortunately, they had a different function in mind when designing them.

Good luck!

So I tried swapping an 18gb in for a 36gb.  I would say it is halfway successful.  I hit the rescan button once the drive was in and it showed the drive as being 18gb.  However, on my computer it still showed the drive as being 36gb.  Shortly after the drive "failed" probably due to the mismatched drive sizes.  I have a feeling it is because Windows is expecting a virtual drive the same size or something.  I think the problem with the way I want to do this is Windows itself will not recognize a change in drives and not scanning the drives for change in directories.

I put text documents in each drive and swapped 2 of the same 36gb drives into each others bays.  In my computer the text document locations didn't change.  When I took out the two drives the text documents were still there and would open.  So my test was basically showed that the PERC Controller would handle the change but that Windows itself wouldn't support it.

Long story short (too late), hot swapping truly only works for RAID arrays with more than one drive in them.  I guess for my situation I will have to stick to cold swapping :emotion-6: