Gentoo Archives: gentoo-user

From: "Canek Peláez Valdés" <caneko@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] RAID 1 on /boot
Date: Sat, 22 Feb 2014 06:41:38
Message-Id: CADPrc823x=TnUoHEXnOjXyA14HZ=DYrGck2ZHB9RDmvBoKq6pA@mail.gmail.com
In Reply to: [gentoo-user] RAID 1 on /boot by Facundo Curti
1 On Fri, Feb 21, 2014 at 11:27 PM, Facundo Curti <facu.curti@×××××.com> wrote:
2 > Hi all. I'm new in the list, this is my third message :)
3 > First at all, I need to say sorry if my english is not perfect. I speak
4 > spanish. I post here because gentoo-user-es it's middle dead, and it's a
5 > great chance to practice my english :) Now, the problem.
6 >
7 > I'm going to get a new PC with a disc SSD 120GB and another HDD of 1TB. But
8 > in a coming future, I want to add 2 or more disks SSD.
9 >
10 > Mi idea now, is:
11 >
12 > Disk HHD: /dev/sda
13 > /dev/sda1 26GB
14 > /dev/sda2 90GB
15 > /dev/sda3 904GB
16 >
17 > Disk SSD: /dev/sdb
18 > /dev/sdb1 26GB
19 > /dev/sdb2 90GB
20 > /dev/sdb3 4GB
21 >
22 > And use /dev/sdb3 as swap. (I will add more with another SSD in future)
23 > /dev/sda3 mounted in /home/user/data (to save data unused)
24 >
25 > And a RAID 1 with:
26 > md0: sda1+sdb1 /
27 > md1: sda2+sdb2 /home
28 >
29 > (sda1 and sda2 will be made with the flag: write-mostly. This is useful for
30 > disks slower).
31 > In a future, I'm going to add more SSD's on this RAID. My idea is the
32 > fastest I/O.
33 >
34 > Now. My problem/question is:
35 > Following the gentoo's doc, it says I need to put the flag --metadata=0.9 on
36 > the RAID. My question is ¿This will make get off the performance?.
37 >
38 > I only found this document. This says the difference, but nothing about
39 > performance and advantages/disadvantages.
40
41 I don't know the performance differences, if any, but in my tests
42 everything worked with the default metadata (1.2).
43
44 > Another question is, ¿GRUB2 still unsupporting metadata 1.2?
45
46 No, GRUB2 supports it just fine. You just need to use the mdraid1x GRUB2 module.
47
48 > In case that metadata get off performance, and GRUB2 doesn't support this.
49 > ¿Anyone knows how can I fix this to use metadata 1.2?
50
51 It's not necessary.
52
53 > I don't partitioned more, because I saw this unnecessary. I just need to
54 > separate /home in case I need to format the system. But if I need to
55 > separate /boot to make it work, I don't have problems doing that.
56
57 It works fine; I tested it in a virtual machine (and I used systemd,
58 but it should not be significantly different with OpenRC). You can
59 check my steps in [1] and [2] (with LUKS support).
60
61 > But of course, /boot also as RAID...
62
63 It works even with boot being on LVM over RAID.
64
65 > ¿Somebody have any ideas to make it work?
66
67 I didn't tested in a real life machine (I've never been a fan of
68 neither RAID nor LVM), but in a VM it worked without a hitch. Again,
69 check [1] and [2].
70
71 Hope it helps.
72
73 Regards.
74
75 [1] http://article.gmane.org/gmane.linux.gentoo.user/269586
76 [2] http://article.gmane.org/gmane.linux.gentoo.user/269628
77 --
78 Canek Peláez Valdés
79 Posgrado en Ciencia e Ingeniería de la Computación
80 Universidad Nacional Autónoma de México

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Subject Author
Re: [gentoo-user] RAID 1 on /boot "Canek Peláez Valdés" <caneko@×××××.com>