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SME 8 Fresh Install and RAID

Offline devtay

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SME 8 Fresh Install and RAID
« on: September 14, 2012, 01:01:01 AM »
Let me start by saying I have read the manual. I have a question that is not necessarily related to a failure of SME 8, I'm looking for best practices and I don't see anything I can understand that describes my issue.

I understand SME uses software RAID and I don't have a preference between a RAID controller and the software RAID in SME. I have a Dell PowerEdge R2970 with a PERC 5/i Integrated RAID controller. The server came that way and it is a hardware controller. What I decided to do was define each of my drives as individual virtual drives configured as RAID 0. This was my compromise because I can't pull the PERC card and plug into a motherboard sata connector and this configuration is more native to how the software RAID is working with SME - SME manages redundancy. I can't use smartctl because it's incompatible with the RAID controller which I don't like.

With my current config, I expected to have a RAID 5 install with 1 hot swap. This is what I get from mdstat.

Code: [Select]
# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [raid1]
md1 : active raid1 sda1[0] sdb1[1] sdc1[2] sdd1[3]
      104320 blocks [4/4] [UUUU]

md2 : active raid5 sdd2[2] sdc2[3](S) sdb2[1] sda2[0]
      975482368 blocks level 5, 256k chunk, algorithm 2 [3/3] [UUU]

unused devices: <none>

I can see from the above output I have 2 channels and it looks like I have RAID 5 + 1 just like the manual says I should. Unfortunately, I don't have a ton of experience with software RAID and would like someone's opinion. Does this configuration seem optimal for SME 8? I have read

http://wiki.contribs.org/Raid
http://wiki.contribs.org/SME_Server:Documentation:Technical_Manual:Chapter5

My next thought was I could just use the RAID controller to do all the work. It has the ability to monitor for failure and swap a drive as required. I will also regain the ability to check SMART data even though I have to down the server to do it. I am looking for fast, fast, fast.

What I don't want is a configuration that exposes me to risks I can't see right now. The reason I am moving my SME server to new hardware is because the old one has a punctured stripe. I was unable to properly diagnose the failure and ended up replacing all the drives just to have the same problem. To SME the array basically looks like a single drive and SME uses it like a single drive. I was wondering if it was possible that the puncture happened because I have it configured this way?

Does anyone have any experience with this type of configuration or any advise?
You can't stop what's coming. It ain't all waiting on you.

Offline devtay

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Re: SME 8 Fresh Install and RAID
« Reply #1 on: September 17, 2012, 09:42:44 PM »
I went ahead and used the hardware raid. I talked to Dell and they said the controller is built for Linux. System runs much faster now.
You can't stop what's coming. It ain't all waiting on you.

Offline Stefano

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Re: SME 8 Fresh Install and RAID
« Reply #2 on: September 18, 2012, 12:16:38 AM »
remember to install DELL's raid utility to monitor raid status