1 [[!meta title="Easy Software RAID with DragonFly BSD and natacontrol(8)"]]
4 I am running 2.11-DEVELOPMENT DragonFly 64Bit with i5 Core on an IntelĀ® Server-Mainboard S1200BT with 8GB RAM.
5 The Main System is on two Disks mirrored RAID1 with 500GB each.
7 I want to use dfBSD as our company fileserver for important backups. Also I found an old (not much used) Dawi controler (with Sillicon's SiL Chip) with 4 SATA Ports that I want to use for our Backup Fileserver.
10 On an already running System I want to add a cheap inexpensive pool of disks keeping mission critical data.
11 Failure tolerance is more important than speed.
17 ## Don't configure the SATA Adapter in the BIOS
18 Please make sure that the adapter is not configured (after the BIOS just before dfBSD starts) with RAID - just expose the disks individually to Dragonfly. We are going to setup a Software RAID.
20 ## Identifying the disks
21 After booting up the system please check that the Adapter you are going to use is correctly found.
25 atapci1: <SiI 3114 SATA150 controller> port 0xe100-0xe10f,0xe110-0xe113,0xe120-0xe127,0xe130-0xe133,0xe140-0xe147 mem 0xfe4a1000-0xfe4a13ff irq 21 at device 0.0 on pci1
27 ### let natacontrol look out for our possible drives
28 su-4.2# natacontrol list
30 Master: no device present
31 Slave: no device present
33 Master: no device present
34 Slave: no device present
36 Master: ad8 <WDC WD10EALX-009BA0/15.01H15> Serial ATA II
37 Slave: no device present
39 Master: ad10 <WDC WD10EALX-009BA0/15.01H15> Serial ATA II
40 Slave: no device present
42 Master: ad12 <WDC WD10EALX-009BA0/15.01H15> Serial ATA II
43 Slave: no device present
45 Master: ad14 <WDC WD10EALX-759BA1/17.01H17> Serial ATA II
46 Slave: no device present
48 Master: ad16 <WDC WD5000AADS-00S9B0/01.00A01> Serial ATA II
49 Slave: no device present
51 Master: ad18 <WDC WD5000AADS-00S9B0/01.00A01> Serial ATA II
52 Slave: no device present
54 Perfect, there they are: ad10 .. ad18 :-)
57 ### Problems finding the disks?
58 But you see the controller in the dmnesg message?
59 First, maybe natacontrol doesn't find them because the ata channel is not attached.
60 So attach it first! You can operate on the channels with the following commands:
61 natacontrol info channel
62 natacontrol attach channel
63 natacontrol detach channel
64 natacontrol reinit channel
66 Do it, until natacontrol can list all single disks you are going to use.
68 For further investigation you can try out other commands to find the disks:
69 also look out for the disks
71 > kern.disks: ad18 ad16 ad14 ad12 da0 da1 md0
73 You could also use the devattr command:
74 devattr -m driver:disk
76 devattr -d da\* # for example
80 ## Chosing the right RAID
81 You can look around in the intert for various Raid calculators
82 A very helpful page for general info is this one:
83 http://www.icc-usa.com/raid-calculator.asp
84 One of the better: http://kossky.sitesled.com/tools/rcdemo_en.htm
86 As I want to have a Backup Fileserver I am chosing a VERY HIGH fault tolerant kind of RAID10 thing. Certainly there are other maybe better ones around, like the RAID60 or even RAID50 but we have to consider what the nata(4) driver offers and that I only have 4 disks.
88 Looking at the man page of natacontrol(8) we see our software RAID options:
90 create Create a type ATA RAID. The type can be RAID0 (stripe), RAID1
91 (mirror), RAID0+1, SPAN or JBOD. In case the RAID has a RAID0
92 component, the interleave must be specified in number of sec-
93 tors. The RAID will be created of the individual disks named
96 Dont worry, natacontrol is offering more than the listed spanning RAIDs and mirroring options.
98 Looking into the source code on DragonFly's OpenGrok we find more options than the man pages lists:
100 lynx http://pkgbox64.dragonflybsd.org/source/xref/DragonFly-master/sys/sys/nata.h
102 struct ata_ioc_raid_config {
105 #define AR_JBOD 0x0001
106 #define AR_SPAN 0x0002
107 #define AR_RAID0 0x0004
108 #define AR_RAID1 0x0008
109 #define AR_RAID01 0x0010
110 #define AR_RAID3 0x0020
111 #define AR_RAID4 0x0040
112 #define AR_RAID5 0x0080
114 Ah, so we can use more than the man page documents!
116 RAID5 is the most versatile RAID, and suitable for normal servers - Home and Office use - but in my opinion too inefficient for a backup space with financial and accounting data.
118 As I only have 4 1TB disks I think RAID0+1 is the best solution as mentioned above.
121 ## Creating the Array
123 Let's dive into real world practice:
125 Just to be sure we don't overwrite the wrong disks we could list them again:
126 natacontrol create RAID10 128 ad8 ad10 ad12 ad14
128 Interestingly RAID10 is accepted, I think it is just a synonym for RAID0+1.
129 The 128 is the interleave I used - which should be reasonable for this kind of setup.