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Ole Tange
Asked: 2011-06-30 05:06:07 +0800 CST

lsscsi finds sas device but none is listed in /dev

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I have a server with 2 internal disks with Adaptec hardware RAID and an external disk box connected via SAS.

lsscsi finds all the devices:

# lsscsi
[0:0:0:0]    disk    Adaptec  System           V1.0  /dev/sda
[0:1:0:0]    disk    WDC      WD1003FBYX-0     01.0  -       
[0:1:1:0]    disk    WDC      WD1003FBYX-0     01.0  -       
[1:0:0:0]    disk    Promise  VessRAID 1840s   0304  -

The first 3 are the 2 physical disks and the hardware RAID on top of those.

The 4th is the external diskbox connected via SAS.

As you can see there is no corresponding device in /dev for the external VessRAID.

The VessRAID is an external SAS-RAID box that presents itself as a SAS device. Linux clearly sees the device, but somehow it does not make it into a device in /dev.

There are two logical drives on the VessRAID.

I have the feeling I need to tell Linux that this is a SAS disk device that Linux should use and scan for logical drives and make them show up in /dev. But I have been unable to find the the magical command that does this.

Digging around /sys gave this:

# cat /sys/class/bsg/1\:0\:0\:0/device/model
VessRAID 1840s  
# cat /sys/class/bsg/1\:0\:0\:0/device/vendor 
Promise

Again this confirms that Linux sees the device, which is already known.

/dev/disk/* sees the RAID'ed internal disks as one device with 2 partition. It does not see the external disk:

# ls -al /dev/disk/by-path
total 0
drwxr-xr-x 2 root root 100 Jun 29 17:06 .
drwxr-xr-x 5 root root 100 Jun 29 17:06 ..
lrwxrwxrwx 1 root root   9 Jun 29 17:06 pci-0000:02:00.0-scsi-0:0:0:0 -> ../../sda
lrwxrwxrwx 1 root root  10 Jun 29 17:06 pci-0000:02:00.0-scsi-0:0:0:0-part1 -> ../../sda1
lrwxrwxrwx 1 root root  10 Jun 29 17:06 pci-0000:02:00.0-scsi-0:0:0:0-part2 -> ../../sda2
hard-drive sas dev

1 Answers

  1. Best Answer

    The problem was not in the Linux end but in the storage end. What was needed was assigning Linux as an initiator on the storage device and disable LUN Masking.

    After doing that I simply modprobe -r mptsas;sleep 1; modprobe mptsas to force a rescan. Then the disks showed up in lsscsi:

    [0:0:0:0]    disk    Adaptec  System           V1.0  /dev/sda
[0:1:0:0]    disk    WDC      WD1003FBYX-0     01.0  -       
[0:1:1:0]    disk    WDC      WD1003FBYX-0     01.0  -       
[4:0:0:0]    disk    Promise  VessRAID 1840s   0304  /dev/sdb
[4:0:0:1]    disk    Promise  VessRAID 1840s   0304  /dev/sdc
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