Prev: NYC LOCAL: Tuesday 13 April 2010 Lisp NYC Meet and NYLUG Hack Meet
Next: Sound input device?
From: unruh on 13 Apr 2010 20:52

I have a raid 0 array, with two partitions, /dev/sdb3 and /dev/sda3 as
parts of that raid 0 array. Disk sdb3 has gone bad (a whole bunch of bad
sectors in previously good data-- and the errors are all on sdb.) so I
have to replace it. Now I have a backup of most of the data (
unfortunately it got done only after the disk started going bad, so some
files are gone for good, but I can live with that). How do I go about
replacing disk b? I assume that there is no way of doing it directly--
ie I have lost all of the data on both disks, and the data that sits on
sda3 is useless. But do I put in the new disk, partition it to have a
sdb3 of the same size as before, and use mdadm to create a new array?
Will the fact that sda3 was a member of that old array cause problems?
Do I reformat sda3?

Once I have the new array set up, I have to restore from the backup I
presume.

(I am using a raid0 to get the speed. Pictures flowing down a GB
ethernet from a GiGE camaera need to get dumped to disk so to get a fast
enough disk transfer to handle full speed GiGE, I need the raid0)

Thanks
Bill Unruh
From: Robert Heller on 13 Apr 2010 21:11
At Wed, 14 Apr 2010 00:52:40 GMT unruh <unruh(a)wormhole.physics.ubc.ca> wrote:

>
>
> I have a raid 0 array, with two partitions, /dev/sdb3 and /dev/sda3 as
> parts of that raid 0 array. Disk sdb3 has gone bad (a whole bunch of bad
> sectors in previously good data-- and the errors are all on sdb.) so I
> have to replace it. Now I have a backup of most of the data (
> unfortunately it got done only after the disk started going bad, so some
> files are gone for good, but I can live with that). How do I go about
> replacing disk b? I assume that there is no way of doing it directly--
> ie I have lost all of the data on both disks, and the data that sits on
> sda3 is useless. But do I put in the new disk, partition it to have a
> sdb3 of the same size as before, and use mdadm to create a new array?

Yes.

> Will the fact that sda3 was a member of that old array cause problems?

No, mdadm -C should create the array 'from scratch'.

> Do I reformat sda3?

mdadm will take care of this.

> Once I have the new array set up, I have to restore from the backup I
> presume.

Yes.

>
> (I am using a raid0 to get the speed. Pictures flowing down a GB
> ethernet from a GiGE camaera need to get dumped to disk so to get a fast
> enough disk transfer to handle full speed GiGE, I need the raid0)
>
> Thanks
> Bill Unruh
>

--
Robert Heller -- Get the Deepwoods Software FireFox Toolbar!
Deepwoods Software -- Linux Installation and Administration
http://www.deepsoft.com/ -- Web Hosting, with CGI and Database
heller(a)deepsoft.com -- Contract Programming: C/C++, Tcl/Tk


From: J G Miller on 14 Apr 2010 08:50
On Wed, 14 Apr 2010 00:52:40 +0000, Unruh wrote:

> I have a raid 0 array, with two partitions, /dev/sdb3 and /dev/sda3 as
> parts of that raid 0 array.

Just a reminder in case it has been overlooked, but in the partition
tables for the disks, the partitions sda3 and sdb3 should be set to

fd Linux raid auto
From: unruh on 14 Apr 2010 11:00
On 2010-04-14, J G Miller <miller(a)yoyo.ORG> wrote:
> On Wed, 14 Apr 2010 00:52:40 +0000, Unruh wrote:
>
>> I have a raid 0 array, with two partitions, /dev/sdb3 and /dev/sda3 as
>> parts of that raid 0 array.
>
> Just a reminder in case it has been overlooked, but in the partition
> tables for the disks, the partitions sda3 and sdb3 should be set to
>
> fd Linux raid auto

Is there a difference between that and 83 Linux ?
From: J G Miller on 14 Apr 2010 11:26
On Wed, 14 Apr 2010 15:00:17 +0000, Unruh asked:

> Is there a difference between that and 83 Linux ?

Yes.

83 is Linux (as in ext2/ext3/ext4) and fd is Linux raid auto.

If the partition type is not correctly set, then the Linux kernel
will not have the correct information about which partitions are
being used for RAID, and therefore will be unable to auto-detect
and automatically manage the RAID array.

From <http://en.gentoo-wiki.COM/wiki/RAID/Software>

QUOTE

When you partition your disks, make sure that your partitions use fd
(Linux RAID autodetect) as Partition Type instead of the default 83
(Linux native) or 82 (swap).

UNQUOTE

Also, I hope that when you create the file system on your RAID array,
you use the most suitable parameters (stride, stride_width) for
the type of RAID in order to optimize performance.

See calculator at <http://busybox.NET/~aldot/mkfs_stride.html>
 |  Next  |  Last
Pages: 1 2
Prev: NYC LOCAL: Tuesday 13 April 2010 Lisp NYC Meet and NYLUG Hack Meet
Next: Sound input device?