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I have a Dell T410 server with a RAID (Perc) card on it and 3 disks of 500GB. When I boot the server, I can see the configuration as Raid 5. But when I try to install Ubuntu 10.04 LTS, I always see the 3 disks. I expected Ubuntu to see only one disk of 1TB

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Does your kernel have support for a PERC6 card? (Assuming it is PERC6. Support fro PERC5 is available if you use kernel 2.6 or higher). It the relevant driver loaded? Either as module or build into a monolithic kernel? –  Hennes Jul 19 '12 at 16:57
    
From what I see, Ubuntu 10.04 LTS use kernel 2.6.32. And it is a "RAID 5,PERC S100 Cntrl" in the server. How can I make sure that the right driver is loaded ? I'm at the OS install step –  ruddy Jul 19 '12 at 17:05
    
Open a shell prompt and use lsmod to list modules. If it is lacking load the megaraid_sas driver. I'll try to post an answer with the relevant links –  Hennes Jul 19 '12 at 17:17
    
So, should I install complety Ubuntu using one disk and then access the shell prompt ? –  ruddy Jul 19 '12 at 18:00
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2 Answers

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PERC S100 is a Software RAID Card, Guide -> http://dell.to/LZGgsH, as you can see on the page 15 all the supported operating systems are Windows, there is no option to install Linux.

So, or you change your card or you do a Software RAID inside the OS.

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I finally did softraid on the OS. So, the card is currently useless. Thanks. –  ruddy Jul 20 '12 at 21:05
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According to Ubuntu on Dell it should be possible to use the PERC5 using the megaraid_sas driver.

The driver for it should be located in /lib/modules/$kernel-version/kernel/drivers/scsi/megaraid/megaraid_sas.ko

This site has quite some information on using a PERC5 with GNU/linux. I am not going to cut and paste it all. It seems that the driver provides access both to the raw disks (please ignore those) and virtual drives formed from the array. Both of them should be listed via megasasctl.

Short version: Can you boot Ubuntu, open a new shell and try these commands:

  • megasasctl
    If it shows the output below then you have a working and recognise RAID array with the name a0d0. You should be able to install to it.
a0       PERC 5/i Integrated  
a0d0       1024GiB RAID 5   1x3  optimal
a0e8s0     500GiB  a0d0  online
a0e8s1     500GiB  a0d0  online
a0e8s2     500GiB  a0d1  online

If that fails:

  • lsmod (Shows loaded kernel modules) - We are looking for megaraid_sas
  • If not present, modprobe megaraid_sas
  • If not found, put it on a floppy (or I guess these days on anything which mounts. Maybe a USB pendrive?)

Then try the megasasctl command again.

  • If the command is not on the Ubuntu installer disc then you might need to look for a static version of it. Or boot a liveCD which has the command.
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So, should I install complety Ubuntu using one disk and then access the shell prompt ? Currently, I'm trying to install Ubuntu but it doesn't see the whole raid as one disk. –  ruddy Jul 19 '12 at 18:45
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