On Sun Nov 30, 2014 at 06:55:53PM -0800, terrygalant@xxxxxxxxxxxx wrote:
> Hi,
>
> I have a 4-drive RAID-10 array. I've been using mdadm for awhile to
> manage the array, and replace drives as they die without changing
> anything.
>
> Now, I want to increase its size in-place. I'd like to ask for some
> help with a review of my setup and plans on how to do it right.
>
> I'm really open to any advice that'll help me get there without
> blowing this all up!
>
> My array is
>
> cat /proc/mdstat
> ...
> md2 : active raid10 sdd1[1] sdc1[0] sde1[4] sdf1[3]
> 1953519616 blocks super 1.2 512K chunks 2 far-copies [4/4] [UUUU]
> bitmap: 0/466 pages [0KB], 2048KB chunk
> ...
>
A question was raised just recently about reshaping "far" RAID10 arrays.
Neil Brown (the md maintainer) said:
I recommend creating some loop-back block devices and experimenting.
But I'm fairly sure that "far" RAID10 arrays cannot be reshaped at all.
> it's comprised of 4 drives; each is 1TB physical size, partitioned
> with a single 'max size' partition, where that partition is formatted
> 'Linux raid autodetect'
>
> fdisk -l /dev/sd[cdef]
>
> Disk /dev/sdc: 931.5 GiB, 1000204886016 bytes, 1953525168 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
> Disklabel type: dos
> Disk identifier: 0x00000000
>
> Device Boot Start End Sectors Size Id Type
> /dev/sdc1 63 1953520064 1953520002 931.5G fd Linux raid autodetect
>
> Disk /dev/sdd: 931.5 GiB, 1000204886016 bytes, 1953525168 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
> Disklabel type: dos
> Disk identifier: 0x00000000
>
> Device Boot Start End Sectors Size Id Type
> /dev/sdd1 63 1953520064 1953520002 931.5G fd Linux raid autodetect
>
> Disk /dev/sde: 931.5 GiB, 1000204886016 bytes, 1953525168 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
> Disklabel type: dos
> Disk identifier: 0x00000000
>
> Device Boot Start End Sectors Size Id Type
> /dev/sde1 63 1953520064 1953520002 931.5G fd Linux raid autodetect
>
> Disk /dev/sdf: 931.5 GiB, 1000204886016 bytes, 1953525168 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
> Disklabel type: dos
> Disk identifier: 0x00000000
>
> Device Boot Start End Sectors Size Id Type
> /dev/sdf1 63 1953520064 1953520002 931.5G fd Linux raid autodetect
>
> the array contains only/multiple LVs, in a RAID-10 array size of 2TB,
>
> pvs /dev/md2
> PV VG Fmt Attr PSize PFree
> /dev/md2 VGBKUP lvm2 a-- 1.82t 45.56g
> vgs VGBKUP
> VG #PV #LV #SN Attr VSize VFree
> VGBKUP 1 8 0 wz--n- 1.82t 45.56g
> lvs VGBKUP
> LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
> LV001 VGBKUP -wi-ao--- 1.46t
> LV002 VGBKUP -wi-ao--- 300.00g
> LV003 VGBKUP -wi-ao--- 160.00m
> LV004 VGBKUP -wi-ao--- 12.00g
> LV005 VGBKUP -wi-ao--- 512.00m
> LV006 VGBKUP -wi-a---- 160.00m
> LV007 VGBKUP -wi-a---- 4.00g
> LV008 VGBKUP -wi-a---- 512.00m
>
> where, currently, ~45.56G of the phy dev is unused
>
> I've purchased 4 new 3TB drives.
>
> I want to upgrade the existing array of 4x1TB drives to 4x3TB drives.
>
> I want to end up with a single partition, @ max_size == ~ 3TB.
>
> I'd like to do this *in-place*, never bringing down the array.
>
> Iiuc, this IS doable.
>
> 1st, I think the following procedure starts the process correctly:
>
> (1) format each new 3TB drive, with one 1TB partition, as 'linux
> raid autodetect', making sure it's IDENTICAL to the partition layout
> on the current array's disks
>
> (2) with the current array up & running, mdadm FAIL one drive
>
> (3) mdadm remove the FAIL'd drive from the array
>
> (4) physically remove the FAIL'd drive
>
> (5) physically insert the new, pre-formatted 3TB drive
>
> (6) mdadm add the newly inserted drive
>
> (7) allow the array to rebuild, until 'cat /proc/mdstat' says it's done
>
> (8) repeat steps (2) - (7) for each of the three remaining drives.
>
> 2nd, I have to correctly/safely to, in 'some' order
>
> extend the physical partitions on all four drives, or of the array
> (not sure which)
> extend the volume group on the array
> expand, or add, the existing LVMs in the volume group.
>
> I'm really not sure about what steps, in what order to do *here*.
>
> Can anyone verify that my first part is right, and help me out with
> doing the 2nd part right?
>
If it is doable (see comment above), it'll be simpler to just partition
the disks to the final size (or skip partitioning at all) - md will
quite happily accept larger devices added to an array (though it doesn't
use the extra space). Otherwise, your initial steps are correct - though
if you have a spare bay (or even a USB/SATA adapter), you can add the
drive as a spare and then use "mdadm --replace" (you may need a newer
version of mdadm for this) command to flag one of the existing array
members for replacement. This will do a direct copy of the data from the
existing disk to the new one and is quicker (and safer) than fail/add.
You'll then need to grow the array, the volume group, then the LVMs.
As I say above, I think you're out of luck though. I'd recommend
connecting up one of the new drives (if you have a spare bay or can hook
it up externally, do so, otherwise you'll need to fail one of the array
members), then:
- Copy all the data over to the new disk
- Stop the old array
- Remove the old disks and insert the new ones
- Create a new array (with a missing member if you only have 4 bays)
- Copy the data off the single disk and onto the new array
- Add the single disk to the array as the final member
Cheers,
Robin
--
___
( ' } | Robin Hill <robin@xxxxxxxxxxxxxxx> |
/ / ) | Little Jim says .... |
// !! | "He fallen in de water !!" |
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