[Beowulf] Beowulf Storage Node

[Joe Landman]

David N. Lombard wrote:
> On Sun, Apr 12, 2009 at 10:53:09AM -0700, Matt Lawrence wrote:
>> On Sat, 11 Apr 2009, Залетнев Дмитрий wrote:
>>
>>> I have a motherboard with 4x SATAII-ports and without RAID. If I'll 
>>> connect to these ports 4 identical SATAII 250 GB 7200 rpm HDDs and 
>>> install Linux, is it possible to have software RAID 0 using Linux?
>> Sure it is.  The only issue you may run into is that the partition 
>> containing /boot can't be on software RAID, grub & lilo don't know how to 
>> deal with RAID partitions.
> 
> That's not /completely/ true:
> 
>   $ cat /etc/fstab
>   /dev/md1            /        ext3    defaults   1 1
>   /dev/sdb3           swap     swap    defaults   0 0
>   LABEL=SWAP-hda3     swap     swap    defaults   0 0
>   /dev/md2            /home    ext3    defaults   1 2
>   /dev/md0            /boot    ext2    defaults   1 2
>   $
> 
> But, the point well taken in the general RAID case...

/boot can be on RAID0 or RAID1 without a problem.  Higher raids are harder.

root at dualcore:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
[raid4] [raid10]
md4 : active raid1 sdc[0] sdd[1]
       732574464 blocks [2/2] [UU]

md3 : active raid1 sda5[0] sdb5[1]
       418910784 blocks [2/2] [UU]

md2 : active raid1 sda3[0] sdb3[1]
       67111424 blocks [2/2] [UU]

md1 : active raid1 sda1[0] sdb1[1]
       264960 blocks [2/2] [UU]

unused devices: <none>
root at dualcore:~# mount | grep md.
/dev/md2 on / type xfs (rw,relatime)
/dev/md4 on /big type xfs (rw,noatime)
/dev/md1 on /boot type ext3 (rw,relatime)
/dev/md3 on /data type xfs (rw,noatime)

Here /, /boot, and other important mounts are set up as software RAID1. 
  Works just fine, and out of the box.

root at dualcore:~# uname -r
2.6.27-11-server


> 
> Also, you clearly don't want *anything* but files that you don't care about
> losing on RAID-0.  If all of your disks are in a RAID-0, booting is only the
> first problem needing a solution.
> 


-- 
Joseph Landman, Ph.D
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