Intro
Back in 2011 we bought Coraid SR2421, simple, fast and relatively cheap network storage device based on AOE (ATA over Ethernet) technology. AoE is lightweight, secure protocol that allows hardware to perform at maximum capacity by sitting directly on top of the Ethernet layer. Its fast because there is no routing, no IP, TCP, or iSCSI to slow down traffic. Quite cool if you ask me.
In 2015 company behind Coraid went busted but I kept using this box as it was (and still is!) rock solid. Now apparently Coraid is back as its intellectual property and trademark was purchased by the founder of AoE’s new company, SouthSuite. They changed their model though, instead of selling appliances they sell software only – which makes sense, you don’t need a middleman selling you pricey hardware when you can get the same equipment directly from the manufacturer for less. Using Coraid software you could even buy used hardware and still get better performance than expensive proprietary SAN devices.
Some features of Coraid:
- Mix and match SSD, SAS, and SATA, including 4K Advanced Format and NVMe.
- Unlimited capacity dictated by disk choice.
- JBOD or RAID 0, 1, 5, 6, or 10 with multiple automatic global spares.
- 1G or 10G SFP+, CX4, and twisted pair NIC options.
- Command Line Interface enables simple provisioning, configuration, and monitoring.
- No TCP/IP overhead.
- Unlimited scale-out storage capacity and IOPS performance.
- Supported natively in Linux kernel since 2005.
- VMware HBAs are available.
- 10x price and performance advantage over Fibre Channel and iSCSI.
What’s even cooler is that they even published guides on how to build your own Coraid box!
Connecting
SR2421 has 2x 1Gbps network cards that can be connected to the switch if you plan connecting more servers. Coraid will automagically use all interfaces to maximize throughput.
I’ve got a single Linux file server with4x 1Gbps. 2x NICs are directly connected to Coraid and remaining 2x NICs are bonded and used to provide service. Important things to remember:
- make sure you bring Coraid facing interfaces up and set MTU to 9000 (jumbo frames) during system boot. Example script here.
- use init script like this one here to mount stuff
Note, Linux box connected to Coraid doesn’t need IP address on the Coraid network card/cards – all data communication happens on lower, Ethernet protocol.
But you need to set IP on Coraid-connected interface if you want syslog feature to work, see Monitoring section below.
Coraid CLI commands
You can either hook up KVM directly to Coraid box or use Coraid Ethernet Console (cec). Once you get to CLI:
SR shelf 0> iostats -d
SR shelf 0> iostats -l
SR shelf 0> sos
SR shelf 0> ifstat -a
SR shelf 0> disks -a
SR shelf 0> make 2 raid5 0.12-16
SR shelf 0> make 3 raid5 0.17-21
RAID levels
• raidL—A linear RAID
• raid0—A striped RAID
• raid1—A mirrored RAID
• raid5—A round-robin parity RAID
• raid6rs—A double fault-tolerant round-robin parity RAID using Reed-Solomon syndromes.
• raid10—A stripe of mirrors RAID.
JBOD
SR shelf 0> jbod 1.0
SR shelf 0> make 0 raidL 1.0
SR shelf 0> online 0
Creating LUN
SR shelf 0> make 2 raid5 0.12-16
SR shelf 0> make 3 raid5 0.17-21
SR shelf 0> online 2
SR shelf 0> online 3
SR shelf 0> label 2 Data Vol 3
SR shelf 0> list
0 15002.965GB online 'Data Vol 1'
1 15002.965GB online 'Data Vol 2'
2 12002.372GB online 'Data Vol 3'
3 12002.372GB online 'Data Vol 4'
SR shelf 0> list -l
0 15002.965GB online 'Data Vol 1'
0.0 15002.965GB raid5 normal
0.0.0 normal 3000.593GB 0.0
0.0.1 normal 3000.593GB 0.1
0.0.2 normal 3000.593GB 0.2
0.0.3 normal 3000.593GB 0.3
0.0.4 normal 3000.593GB 0.4
0.0.5 normal 3000.593GB 0.5
1 15002.965GB online 'Data Vol 2'
1.0 15002.965GB raid5 normal
1.0.0 normal 3000.593GB 0.6
1.0.1 normal 3000.593GB 0.7
1.0.2 normal 3000.593GB 0.8
1.0.3 normal 3000.593GB 0.9
1.0.4 normal 3000.593GB 0.10
1.0.5 normal 3000.593GB 0.11
2 12002.372GB online 'Data Vol 3'
2.0 12002.372GB raid5 normal
2.0.0 normal 3000.593GB 0.12
2.0.1 normal 3000.593GB 0.13
2.0.2 normal 3000.593GB 0.14
2.0.3 normal 3000.593GB 0.15
2.0.4 normal 3000.593GB 0.16
3 12002.372GB online 'Data Vol 4'
3.0 12002.372GB raid5 normal
3.0.0 normal 3000.593GB 0.17
3.0.1 normal 3000.593GB 0.18
3.0.2 normal 3000.593GB 0.19
3.0.3 normal 3000.593GB 0.20
3.0.4 normal 3000.593GB 0.21
SR shelf 7> when
0.0 1.29% 235073 KBps 0:46:06 left
Hot Spares
SR shelf 0> spare
SR shelf 0> spare 0.22-23
SR shelf 0> rmspare 7.6
SR shelf 0> replace 8.0.1 7.12
Restricting access with mac and vlan commands
SR shelf 0> vlan 3 100
SR shelf 0> vlan 4 200
SR shelf 0> vlan 3
3 100
SRX shelf 7> mask -?
usage: mask lun ... [ +mac ... ] [ -mac ... ]
Other useful commands
SR shelf 0> slotled 0 locate # or fault,rebuild,reset,spare
SR shelf 0> fans
FAN# RPM
fan0 4623
fan1 4545
fan2 4591
fan3 3781
fan4 3970
SR shelf 0> power
PSU# STATUS TEMP FAN1RPM
ps0 up 41C 12366
ps1 up 40C 12480
SR shelf 0> temp
LOCATION TEMP
cpu 63C
ps0 41C
ps1 41C
# smart status
SR shelf 0> disks -s
DISK STATUS
0.0 normal
0.1 normal
0.2 normal
0.3 normal
0.4 normal
0.5 normal
0.6 normal
0.7 normal
0.8 normal
0.9 normal
SR shelf 0> eject 4
Are you sure you want to perform this action? y/n? [N]
Ejecting lun(s): 4
# eject command is useful when you want to move a LUN from one shelf to another without shutting down the SR
Using Coraid LUN as LVM backend
When you create new LUN on Coraid console it should be detected by Linux kernel:
# Just making sure we have aoe tools present
root@file-srv:~ # yum info aoetools
Name : aoetools
Arch : x86_64
Version : 36
Release : 3.el6
Size : 90 k
Repo : installed
From repo : epel
Summary : ATA over Ethernet Tools
URL : http://aoetools.sourceforge.net
License : GPLv2
Description : The aoetools are programs that assist in using ATA over Ethernet on
: systems with version 2.6 and newer Linux kernels.
root@file-srv:~ # aoe-stat
e0.0 15002.964GB em2,em1 8704 up
e0.1 15002.964GB em2,em1 8704 up
e0.2 12002.371GB em1,em2 8704 up
e0.3 12002.371GB em1,em2 8704 up
# other tools in the package: aoe-discover, aoe-version, aoe-mkshelf
root@file-srv:~ # dmesg
aoe: e0.2: setting 8704 byte data frames
aoe: 00259022357e e0.2 vace0 has 23442132477 sectors
etherd/e0.2: unknown partition table
aoe: e0.3: setting 8704 byte data frames
aoe: 00259022357e e0.3 vace0 has 23442132477 sectors
etherd/e0.3: unknown partition table
OK, so we are looking at working with device e0.2 and e0.3
root@file-srv:~ # parted /dev/etherd/e0.2
(parted) mktable gpt
(parted) p
Model: Unknown (unknown)
Disk /dev/etherd/e0.3: 12.0TB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
(parted) mkpart primary ext4 0% 100%
(parted) set 1 lvm on
(parted) p
Model: Unknown (unknown)
Disk /dev/etherd/e0.3: 12.0TB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 1049kB 12.0TB 12.0TB primary lvm
(parted)
We have a partition created, lets use it to expand existing LVM volume group
root@file-srv:~ # pvcreate /dev/etherd/e0.2p1
Physical volume "/dev/etherd/e0.2p1" successfully created
root@file-srv:~ # pvcreate /dev/etherd/e0.3p1
Physical volume "/dev/etherd/e0.3p1" successfully created
root@file-srv:~ # vgextend coraid /dev/etherd/e0.2p1
Volume group "coraid" successfully extended
root@file-srv:~ # vgextend coraid /dev/etherd/e0.3p1
Volume group "coraid" successfully extended
root@file-srv:~ # vgs
VG #PV #LV #SN Attr VSize VFree
coraid 4 14 0 wz--n- 49.12t 27.69t
root@file-srv:~ # vgdisplay -v coraid
--- Physical volumes ---
PV Name /dev/etherd/e0.1p1
PV UUID OmPkNP-HJmi-xaeda-1obx-iFHW-n84f-7tbbfo
PV Status allocatable
Total PE / Free PE 3576985 / 748850
PV Name /dev/etherd/e0.0p1
PV UUID y2W3GJ-Rp0E-gxgE-asd-fpQM-DT26-n6Sz0C
PV Status allocatable
Total PE / Free PE 3576985 / 786432
PV Name /dev/etherd/e0.2p1
PV UUID f5pUm2-asqw-tO1q-962I-rGDJ-LzZi-b20zft
PV Status allocatable
Total PE / Free PE 2861587 / 2861587
PV Name /dev/etherd/e0.3p1
PV UUID 94ABPd-ucTT-8vg6-WX5R-awew-Mw4b-dYdoHB
PV Status allocatable
Total PE / Free PE 2861587 / 2861587
All done. Nice and easy. We can now get on with creating LVM volumes, etc.
Monitoring
One important aspect to bear in mind is Coraid monitoring. My dirty way of solving that is to configure Coraid to send logs to syslog (UDP port 514) on connected server and then run cronjob that will alert me on any Coraid-related event.
Preparing Coraid
# syslog -cp ServerDestinationIP CoraidSourceIP LocalSRinterface
syslog -cp 10.0.0.1 10.0.0.100 ether0
Preparing Linux server, cronjob script that runs every hour or so:
#!/bin/bash
#########################################################################################
# 2011-09-01: Quick and dirty, monitoring coraid
# Send bugreports, fixes, enhancements, t-shirts, money, beer & pizza to devnull at mielnet.pl"
TODAYONLY=`date "+%b %e"`
grep "$TODAYONLY" /var/log/messages|grep shelf > /tmp/coraid.out
######### if coraid.out exists and size > 0
if [ -s /tmp/coraid.out ]
then
######## send it to me
cat /tmp/coraid.out |mail -s "Problem with ABC Coraid" [email protected]
######## otherwise just go away
else exit 0
fi
######### cleanup
rm /tmp/coraid.out
######################## eof ############################################################
Why
I’m a big fan of this solution. If you are still not convinced, I’ll show you why:
SR shelf 0> uptime
up 632 days, 17:36:38