1 |
On 04/02/10 07:59, Mark Knecht wrote: |
2 |
>Good questions: |
3 |
> |
4 |
>1) Yes, you can RAID partitions of drives. That's what I'm doing. You |
5 |
>can look at the Gentoo RAID/LVM Install guide to see an example of |
6 |
>using RAID0 and RAID1 on a single drive. |
7 |
> |
8 |
>http://www.gentoo.org/doc/en/gentoo-x86+raid+lvm2-quickinstall.xml |
9 |
> |
10 |
>2) I'm certainly not suggesting RAID doesn't work. It's just not |
11 |
>working for me, either due to new motherboard hardware or due to the |
12 |
>drives themselves. I'm currently betting it's the drives. The |
13 |
>background info, without getting too deeply into it, is that if the |
14 |
>drive supports SMART and SMART is enabled, then when doing RAID you |
15 |
>need guaranteed Time Limited Error Recovery (TLER) to ensure (I think) |
16 |
>that SMART works doesn't get in the way of the drive responding in the |
17 |
>appropriate amount of time or else the drive will fall out of the RAID |
18 |
>array. Turns out the WD (according to different mailing list and |
19 |
>forums I've been looking at) has removed TLER on almost all of their |
20 |
>Green drive and some/many/most of the Blue and Black series. They are |
21 |
>supporting this in the RE drives though of which I've obtained two. |
22 |
>They are smaller and more expensive, but built for RAID, so I'm going |
23 |
>to try them out next. |
24 |
> |
25 |
>http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery |
26 |
> |
27 |
>3) As I understand the subject you are correct about size and speed, |
28 |
>but a 3-disk RAID5 array can stand 1 disk failing whereas a 3-disk |
29 |
>RAID1 array can stand 2 disks failing. For this app (MythTV and seldom |
30 |
>used backup server) I don't need speed and size isn't a huge issue so |
31 |
>I chose 3-disk RAID1. (Note that the HTPC case I'm using supports up |
32 |
>to 3 drives only.) Because multiple drives purchased at the same time |
33 |
>generally come from the same production lot there's an additional |
34 |
>danger that if one drive fails then one more (or all) could fail at |
35 |
>the same time so I'm protecting myself against that. Again, this is |
36 |
>very specific to my current needs which is really to back up another |
37 |
>machine which will be RAID0 as it needs more disk I/O speed to support |
38 |
>12 processor cores. |
39 |
> |
40 |
>As always, I'm certainly interested in info and ideas on this subject, |
41 |
>most especially now when I'm buying and building. |
42 |
> |
43 |
>Cheers, |
44 |
>Mark |
45 |
|
46 |
I'm not even sure if any RAID is a solution for me. |
47 |
My situation is a follow, I've configured Gentoo box for a medical clinic and I'll administer it reportedly via ssh. |
48 |
One server running Windows XP in VirtualBox and some other Linux programs. |
49 |
Server is a quad core ADM and has two identical SATA drives about 600GB |
50 |
There is another smaller box (Intel ATOM CPU) running Gentoo, this box runs Asterisk and VirtualBox as well, it is a server backup. If something happens to |
51 |
mains Server, user just presses "Scroll Lock" twice (KVM), logs in into smaller and runs the main program from there. So I have a backup in place. |
52 |
|
53 |
I just want to utilize the second drive of the main server. I'm mostly concerns about the problems with emerge, not the hard drive failure (I've plenty of |
54 |
backups). |
55 |
So, I think the best option for me is to just mirror the first HD and modify it to use it a sdb. I'm just making steps I need to do: |
56 |
|
57 |
1.) Boot from external CD |
58 |
dd if=/dev/sda of=/dev/sdb |
59 |
|
60 |
2.) |
61 |
modify (add to) grub.conf on sda |
62 |
#title boot sda current |
63 |
title=1st HD sda Kernel Current |
64 |
root (hd0,0) |
65 |
kernel /boot/kernel-current root=/dev/sda3 |
66 |
|
67 |
#title boot sdb current |
68 |
title=2nd HD sdb Kernel Current |
69 |
root (hd1,0) |
70 |
kernel /boot/kernel-current root=/dev/sdb3 |
71 |
|
72 |
3.) Modify fstab |
73 |
|
74 |
Walt has mentioned to use "rdev" but reading man pages it is only i386, and all my boxes running amd64 (x86_64). |
75 |
|
76 |
What else did I miss. |
77 |
|
78 |
-- |
79 |
Joseph |