Ampersand

From CSLabsWiki
Jump to: navigation, search
Ampersand
IP Address(es): DHCP
Contact Person: xperia64
Last Update: Spring 2016
Services: A Ton of Space
LDAP Support: no


Ampersand is the storage array donated by OIT. It's a DELL MD3000i with 15 2-TiB drives and 30 1-TiB drives. It is currently being used for The-Internet


Setup

The array can be managed with the DELL Modular Disk Storage Manager software. Currently, we have only ever gotten the software running on Windows, as it appears only Redhat 5 and SUSE 11 and older are officially supported. The software will automatically find the array assuming the management ports are on the same subnet, which is why they are set to DHCP. The drives should not be RAID'd with the built in hardware given that it is likely that data will be lost if any part of the array fails. Instead, set up each drive as a single "RAID 0" device, which essentially leaves the disks exposed raw. The iSCSI initiator that the storage array will be used on must be able to connect to all four iSCSI ports on Ampersand and be able to act as a gateway. Currently the iSCSI ports are assigned to 10.0.0.2-10.0.0.5.

Linux Specific Instructions

The storage array requires the following packages:

open-iscsi multipath-tools

iscsid.conf must be edited to include the following changes:

node.startup = automatic
node.leading_login = No
node.session.authmethod = CHAP

The username fields should be left commented out while the sendtargets and session passwords must be set. Run the following command to connect the storage array to the array:

iscsiadm -m discovery -t st -p 10.0.0.2

Assign drives to the initiator using the DELL MDSM software.

Next, configure multipath-tools by adding this to /etc/multipath.conf

defaults {
	user_friendly_names no
}
devices {
	device {
		vendor DELL*
		product MD3000*
		path_grouping_policy failover
		features "1 queue_if_no_path"
		path_checker rdac
		path_selector "round-robin 0"
		prio rdac
		hardware_handler "1 rdac"
		failback immediate
	}
}
blacklist_exceptions {
	device {
		vendor DELL*
		product MD3000*
	}
}
blacklist {
	devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
	device {
		vendor "Western Digital"
		product "^.+$"
	}
	device {
		vendor "Seagate"
		product "^.+$"
	}
	device {
		vendor "^.+$"
		product "ST*"
	}
	device {
		vendor "^.+$"
		product "^INTEL.+$"
	}
	device {
		vendor "^.+$"
		product "WDC*"
	}
}

Load the necessary kernel module by adding the following to /etc/modules:

scsi_dh_rdac

Consider rebooting to ensure all configuration changes have taken place. Note: Mounting all of the drives may to between 4 and 10 minutes during the boot process. This is normal.

There will be 4 times as many block devices as there are drives attached to the host. This is due to multipath. Do not write to those devices directly. Instead, write to the devices in /dev/mapper/

Serial Interface

To interface with the storage array via the serial cable, configure your favorite serial terminal as follows: 115200 baud 8-N-1 No flow control

Send <BREAK> to the array and immediately press capital 'S' When prompted for a password, enter 'supportDell'