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Old 11-17-2011, 04:01 PM
Mark Knecht
 
Default Process to resize ext3 file system at the command line?

Hi,
I've got a 3-disk 250GB RAID-1 that I use for short term, on the
machine backups. It's normally not mounted unless I'm doing a quick
save. Unfortunately it's a bit too small these days so I'm therefore
going to convert it to a 3-disk RAID-5 which will double it's size.

I'm pretty sure I've got the command set right to do the RAID-1 to
RAID-5 conversion, but once it's done I believe the file system itself
will still be 250GB so I'll need to resize the file system. In the
past I've done this with gparted, which seems to work fine, but this
time I was considering doing it at the command line. Does anyone know
of a good web site that goes through how to do that? I've browsed
around and found different pages that talk about it but my reading
looks like they all have minor differences which leaves me a bit
worried.

Note that the status of the backup is currently good but if I
happen to lose the data on that partition it won't likely be a big
problem. I'm just trying to get to the end of the process without
losing it if possible.

Thanks,
Mark
 
Old 11-17-2011, 04:25 PM
Neil Bothwick
 
Default Process to resize ext3 file system at the command line?

On Thu, 17 Nov 2011 09:01:46 -0800, Mark Knecht wrote:

> I'm pretty sure I've got the command set right to do the RAID-1 to
> RAID-5 conversion, but once it's done I believe the file system itself
> will still be 250GB so I'll need to resize the file system. In the
> past I've done this with gparted, which seems to work fine, but this
> time I was considering doing it at the command line. Does anyone know
> of a good web site that goes through how to do that? I've browsed
> around and found different pages that talk about it but my reading
> looks like they all have minor differences which leaves me a bit
> worried.

Using cfdisk or fdisk, delete the partition and recreate it, USING THE
SAME START BLOCK at a larger size.

Then "resize2fs /dev/sdwhatever" will resize the filesystem to fill the
partition.



--
Neil Bothwick

I just took an IQ test. The results were negative.
 
Old 11-17-2011, 05:29 PM
Mark Knecht
 
Default Process to resize ext3 file system at the command line?

On Thu, Nov 17, 2011 at 9:25 AM, Neil Bothwick <neil@digimed.co.uk> wrote:
> On Thu, 17 Nov 2011 09:01:46 -0800, Mark Knecht wrote:
>
>> * *I'm pretty sure I've got the command set right to do the RAID-1 to
>> RAID-5 conversion, but once it's done I believe the file system itself
>> will still be 250GB so I'll need to resize the file system. In the
>> past I've done this with gparted, which seems to work fine, but this
>> time I was considering doing it at the command line. Does anyone know
>> of a good web site that goes through how to do that? I've browsed
>> around and found different pages that talk about it but my reading
>> looks like they all have minor differences which leaves me a bit
>> worried.
>
> Using cfdisk or fdisk, delete the partition and recreate it, USING THE
> SAME START BLOCK at a larger size.
>
> Then "resize2fs /dev/sdwhatever" will resize the filesystem to fill the
> partition.
>
>
>
> --
> Neil Bothwick

Really? Delete the partition? Sounds scary! (But actually makes sense.
The data is still there.)

I'm not sure how this works in the case of a RAID though. Here's the
current partition table for sda where sda6, sdb6 & sdc6 are part of
the RAID-1::

c2stable ~ # fdisk -l /dev/sda

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x8b45be24

Device Boot Start End Blocks Id System
/dev/sda1 * 63 112454 56196 83 Linux
/dev/sda2 112455 8514449 4200997+ 82 Linux swap / Solaris
/dev/sda3 8594775 113467094 52436160 fd Linux raid autodetect
/dev/sda4 113467095 976768064 431650485 5 Extended
/dev/sda5 113467158 218339414 52436128+ fd Linux raid autodetect
/dev/sda6 481933935 976768064 247417065 83 Linux
/dev/sda7 218339478 481933871 131797197 fd Linux raid autodetect

Partition table entries are not in disk order
c2stable ~ #

It's not that I want to change the partition size of the 3 pieces of
the RAID-1, it's that after I convert the RAID-1 to RAID-5 I want it
to be 500GB.


I asked some questions on the Linux RAID list and putting together
info from a couple of people here's how I'm thinking I proceed with
the conversion:

1) First, fail one disk and clean it up for later:

umount /dev/md6
mdadm --stop /dev/md6
mdadm /dev/md6 --fail /dev/sdc6 --remove /dev/sdc6
mdadm --zero-superblock /dev/sdc6

At this point the RAID-1 is still 3-drives but one is marked 'failed'.
The failed drive is at this point like a new drive as it has no
superblock. (I think...)

2) Now I convert the 3-drive RAID1 to a 2-drive RAID-1:

mdadm --grow /dev/md6 --raid-devices=2

3) Create a 2-drive RAID-5:

mdadm has an 'instantaneous' conversion of RAID-1 to RAID-5 for the
2-drive case because parity of a single drive is just the data itself.
/dev/sdb6 is now 'parity' instead of 'data'.

mdadm /dev/md6 --grow --level=5

4) Add a 3rd drive to the RAID-5:

mdadm /dev/md6 --add /dev/sdc6
mdadm /dev/md6 --grow --raid-devices=3



At this point I was told:

"Now, resize your filesystem to use the additional space."

So, if at this point the end-block of sda6 isn't 976768064 but, let's
say, 700000000 because mdadm set it to something new, then using your
suggestion I guess I'd set it back to 976768064? I'm not comfortable
however that if I do that that whatever is out there beyond 700000000
is really formatted as ext3 and 'empty' as I don't know what the mdadm
conversion has done to it.


Thanks,
Mark
 
Old 11-17-2011, 05:43 PM
Michael Mol
 
Default Process to resize ext3 file system at the command line?

On Thu, Nov 17, 2011 at 1:29 PM, Mark Knecht <markknecht@gmail.com> wrote:
> On Thu, Nov 17, 2011 at 9:25 AM, Neil Bothwick <neil@digimed.co.uk> wrote:
>> On Thu, 17 Nov 2011 09:01:46 -0800, Mark Knecht wrote:
>>
>>> * *I'm pretty sure I've got the command set right to do the RAID-1 to
>>> RAID-5 conversion, but once it's done I believe the file system itself
>>> will still be 250GB so I'll need to resize the file system. In the
>>> past I've done this with gparted, which seems to work fine, but this
>>> time I was considering doing it at the command line. Does anyone know
>>> of a good web site that goes through how to do that? I've browsed
>>> around and found different pages that talk about it but my reading
>>> looks like they all have minor differences which leaves me a bit
>>> worried.
>>
>> Using cfdisk or fdisk, delete the partition and recreate it, USING THE
>> SAME START BLOCK at a larger size.
>>
>> Then "resize2fs /dev/sdwhatever" will resize the filesystem to fill the
>> partition.
>>
>>
>>
>> --
>> Neil Bothwick
>
> Really? Delete the partition? Sounds scary! (But actually makes sense.
> The data is still there.)
>
> I'm not sure how this works in the case of a RAID though. Here's the
> current partition table for sda where sda6, sdb6 & sdc6 are part of
> the RAID-1::
>
> c2stable ~ # fdisk -l /dev/sda
>
> Disk /dev/sda: 500.1 GB, 500107862016 bytes
> 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x8b45be24
>
> * Device Boot * * *Start * * * * End * * *Blocks * Id *System
> /dev/sda1 * * * * * * *63 * * *112454 * * * 56196 * 83 *Linux
> /dev/sda2 * * * * *112455 * * 8514449 * * 4200997+ *82 *Linux swap / Solaris
> /dev/sda3 * * * * 8594775 * 113467094 * *52436160 * fd *Linux raid autodetect
> /dev/sda4 * * * 113467095 * 976768064 * 431650485 * *5 *Extended
> /dev/sda5 * * * 113467158 * 218339414 * *52436128+ *fd *Linux raid autodetect
> /dev/sda6 * * * 481933935 * 976768064 * 247417065 * 83 *Linux
> /dev/sda7 * * * 218339478 * 481933871 * 131797197 * fd *Linux raid autodetect
>
> Partition table entries are not in disk order
> c2stable ~ #
>
> It's not that I want to change the partition size of the 3 pieces of
> the RAID-1, it's that after I convert the RAID-1 to RAID-5 I want it
> to be 500GB.
>
>
> I asked some questions on the Linux RAID list and putting together
> info from a couple of people here's how I'm thinking I proceed with
> the conversion:
>
> 1) First, fail one disk and clean it up for later:
>
> umount /dev/md6
> mdadm --stop /dev/md6
> mdadm /dev/md6 --fail /dev/sdc6 --remove /dev/sdc6
> mdadm --zero-superblock /dev/sdc6
>
> At this point the RAID-1 is still 3-drives but one is marked 'failed'.
> The failed drive is at this point like a new drive as it has no
> superblock. (I think...)
>
> 2) Now I convert the 3-drive RAID1 to a 2-drive RAID-1:
>
> mdadm --grow /dev/md6 --raid-devices=2
>
> 3) Create a 2-drive RAID-5:
>
> mdadm has an 'instantaneous' conversion of RAID-1 to RAID-5 for the
> 2-drive case because parity of a single drive is just the data itself.
> /dev/sdb6 is now 'parity' instead of 'data'.
>
> mdadm /dev/md6 --grow --level=5
>
> 4) Add a 3rd drive to the RAID-5:
>
> mdadm /dev/md6 --add /dev/sdc6
> mdadm /dev/md6 --grow --raid-devices=3
>
>
>
> At this point I was told:
>
> "Now, resize your filesystem to use the additional space."
>
> So, if at this point the end-block of sda6 isn't 976768064 but, let's
> say, 700000000 because mdadm set it to something new, then using your
> suggestion I guess I'd set it back to 976768064? I'm not comfortable
> however that if I do that that whatever is out there beyond 700000000
> is really formatted as ext3 and 'empty' as I don't know what the mdadm
> conversion has done to it.

Your resize would be applied not to /dev/sd?, but to /dev/md?. You
don't need to worry about what that means on /dev/sd*; the filesystem
you want to poke is on /dev/md*.

file -s /dev/sd* /dev/md*

--
:wq
 
Old 11-17-2011, 05:59 PM
Mark Knecht
 
Default Process to resize ext3 file system at the command line?

On Thu, Nov 17, 2011 at 10:43 AM, Michael Mol <mikemol@gmail.com> wrote:
> On Thu, Nov 17, 2011 at 1:29 PM, Mark Knecht <markknecht@gmail.com> wrote:
<SNIP>
>> At this point I was told:
>>
>> "Now, resize your filesystem to use the additional space."
>>
>> So, if at this point the end-block of sda6 isn't 976768064 but, let's
>> say, 700000000 because mdadm set it to something new, then using your
>> suggestion I guess I'd set it back to 976768064? I'm not comfortable
>> however that if I do that that whatever is out there beyond 700000000
>> is really formatted as ext3 and 'empty' as I don't know what the mdadm
>> conversion has done to it.
>
> Your resize would be applied not to /dev/sd?, but to /dev/md?. You
> don't need to worry about what that means on /dev/sd*; the filesystem
> you want to poke is on /dev/md*.
>
> file -s /dev/sd* /dev/md*
>
> --
> :wq

Yes, resize would be done to /dev/md?. I agree. However I don't
believe that I'd use Neil's suggestion of fdisk block numbers on
/dev/md, right? That doesn't make sense to me and I don't beleieve
Neil was suggesting anything like that.

I'm thinking that possibly the mdadm way to change the _size_ of a
RAID is to once again use the grow option:

<quote>
-G, --grow
Change the size or shape of an active array.
<quote>

I've not yet found any instructions that I trust to do it though, and
being that the instructions above came from, among others, Neil Brown
who manages mdadm I'm hesitant to go in my own direction. I'm just
looking before I leap.

And fortunately, if I decided to just blow away all three disks and
start from scratch I have very little at risk that way, and very
little risk as I will do backups of the RAID-1 onto an external USB
drive before I start this process anyway.

- Mark
 
Old 11-17-2011, 06:13 PM
Michael Mol
 
Default Process to resize ext3 file system at the command line?

On Thu, Nov 17, 2011 at 1:59 PM, Mark Knecht <markknecht@gmail.com> wrote:
> On Thu, Nov 17, 2011 at 10:43 AM, Michael Mol <mikemol@gmail.com> wrote:
>> On Thu, Nov 17, 2011 at 1:29 PM, Mark Knecht <markknecht@gmail.com> wrote:
> <SNIP>
>>> At this point I was told:
>>>
>>> "Now, resize your filesystem to use the additional space."
>>>
>>> So, if at this point the end-block of sda6 isn't 976768064 but, let's
>>> say, 700000000 because mdadm set it to something new, then using your
>>> suggestion I guess I'd set it back to 976768064? I'm not comfortable
>>> however that if I do that that whatever is out there beyond 700000000
>>> is really formatted as ext3 and 'empty' as I don't know what the mdadm
>>> conversion has done to it.
>>
>> Your resize would be applied not to /dev/sd?, but to /dev/md?. You
>> don't need to worry about what that means on /dev/sd*; the filesystem
>> you want to poke is on /dev/md*.
>>
>> file -s /dev/sd* /dev/md*
>>
>> --
>> :wq
>
> Yes, resize would be done to /dev/md?. I agree. However I don't
> believe that I'd use Neil's suggestion of fdisk block numbers on
> /dev/md, right? That doesn't make sense to me and I don't beleieve
> Neil was suggesting anything like that.
>
> I'm thinking that possibly the mdadm way to change the _size_ of a
> RAID is to once again use the grow option:
>
> <quote>
> * * * -G, --grow
> * * * * * * *Change the size or shape of an active array.
> <quote>
>
> I've not yet found any instructions that I trust to do it though, and
> being that the instructions above came from, among others, Neil Brown
> who manages mdadm I'm hesitant to go in my own direction. I'm just
> looking before I leap.
>
> And fortunately, if I decided to just blow away all three disks and
> start from scratch I have very little at risk that way, and very
> little risk as I will do backups of the RAID-1 onto an external USB
> drive before I start this process anyway.

Ok, I thought you had it clear how you were going to resize the raid,
and needed help resizing the filesystem that already existed on top of
the RAID. I interpreted Mark's instructions as operating under that
impression, too.

Are you saying you don't already have a partition table sitting on top
of /dev/md? ?


--
:wq
 

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