RAID 5 array failure time?

[nachamiyahu]

I was wondering is there any way to calculate or even estimate how long a RAID-5 array would last if a drive had failed and been pulled. I had a failed drive which i pulled and left my server off for a week waiting for the replacement. When i plugged said replacement drive in, driver manager registered my array as "failed". So now I'm in the process of formatting and re creating a new array from scratch. And I'm using WHS 2011's RAID 5 software.

 

[abbadon_34]

Were you using the degraded array in ANY WAY, even simple powered on, in meantime? Is this a true hardware raid, a pseudo-hardware/software raid, or a windows/software raid? Your array DID fail, one drive is gone, but the new drive should allow for rebuilding. You should be rebuilding the array to it's prior state, or waiting on a new drive if the replacement is bad. It sounds like you may have selected the incorrect option.

 

[nachamiyahu]

It is a windows software Raid. During the downtime between getting the drive replaced by the manufacturer I powered the machine down. When I put the new drive in and powered the machine back up. Disk management read that the array had failed. And it gave me no other options with the new drive other than creating a new volume. And now its been brought to my attention by a friend of mine that I may not even be able to use this new drive because it is a WD red drive and my other 2 drives are WD Green.

 

[abbadon_34]

The type of drives general don't matter, but it is best to be of same size, if not make and model. It sounds like the new drive wasn't assigned to the array. If it not auto assigned, it just shows up like any other drive. Once is get assigned to the array the option to rebuild will be from the array. For some reason if you click on the drive you get different options than if you click on the Disk # in the box next to it.

If the array is up and running, you are able to rebuild. The time you have to do so is based on the chance that one of the remaining die first. Look up hd failure rates and do the math.

 

[nachamiyahu]

So where would I click if I wanted to assign a new drive to the array? And I just tried what you said i.e. clicking on the drive partition rather than the disk number. And I now see what you are referring to in that regard. Wish I had seen that last night while trouble shooting. Live and learn I suppose.

 

[abbadon_34]

You did make it dynamic first right?

 

[nachamiyahu]

Yes assuming the disks have been made dynamic. Also could you detail the steps I would take if, like last time I turned my server on and found that the array had failed. I just wanna make sure.

 

[abbadon_34]

Since I do not use Windows Home Sever 2011 on regular basis, I would direct you to MS CS. The real answers, not the community answers. Maybe start with http://technet.microsoft.com/en-us/library/cc757431

 

[nachamiyahu]

I read the article and I think that will help me if/when I have another hard drive failure or when I decide to upgrade my other 2 drives to WD red. Btw if I'm using RAID 5 does that mean I couldn't "swap" drives out, like for instance ive got 3-2tb drives and i wanna swap them for 3-3tb drives? Or is that not considered drive extending which i know is not possible with RAID 5.

 

[abbadon_34]

I don't *think* WHS2011 has that option, you would a need a true hardware RAID or psuedo-hardware RAID to do that without wiping them all. Replacing a 2TB with a 3TB would just only use 2TB, outside any sector size issues.

This article shows exanding a RAID5 via a combination of Intel RST and WHS2011. Since I don't know you hardware I can't say if it's of any help. Skip to "Can you expand the RAID 5 Array?"

http://homeservershow.com/dual-raid-setup-on-windows-home-server-2011-and-adding-drives-to-a-raid-5-array.html

 

[nachamiyahu]

I see what you're saying. And I came up with the same conclusion as well after thinking about it. On the subject of hot swapping. My friend was able to hot swap drives and it would auto-detect it. But he left the machine running while he swapped it. I'm thinking that may make a difference next time I come up against this issue. I wish there was a way to replicate the situation I faced before. From the MS article you posted it seems that if I wanted to replace a failed drive with a new one and add it to the array I would: make it dynamic and then i would right click the partition of the new drive and select "new raid volume"? or would I got up to the top of the page and right click the whole volume and select "repair volume"?

 

[abbadon_34]

Hot swapping is a more a function of the interface. IDE does not support it, SCSI does, and SATA will *as long as* compatible SATA connectors are used (not legacy molex and IDE adapters). This is along with specialized hardware solutions. RAID was originally designed around hot-swappable enterprise environments, but has trickeled down to consumer level uses.

As for replacing a failed drive, with 2003/2008 server (I assume but can't say for sure with 2011) the "repair volume" would be correct. If they are still basic disks repair volume would most likely be grey out, but supposedly selectable if a second "spare" is connected and viable.

 

[nachamiyahu]

Well whs11 is just win server 2008 a little nicer looking and way cheaper so the same would apply to both. When the drives are finished formatting I will test trying to resync the array in a failed state. And I'll let ya know what happens. Thanks for all the help.