(Online Capacity Expansion for IMSM)
The following series implements Online Capacity Expansion in mdadm for Raid0 or Raid5 arrays build on IMSM's metadata.
It allows for adding new hard drive(s) to existing IMSM Raid0 or Raid5 array.
Online Capacity Expansion for External Metadata requires Takeover functionality in md and mdadm.
Algorithm looks as follows:
1. mdadm: For Raid0 array, execute takeover to Raid5
2. mdadm: set new raid disks number to md using raid_disks entry in sysfs
3. mdadm: call update_super() to configure added disks from spares pool (add them to md configuration) and prepare metadata update
4. mdadm: run reshape using sync_action entry in sysfs
5. md : starts reshape
6. mdmon: detects change in md configuration (increases number of disks)
7. mdmon: reallocates active_array structure and external metadata specific structures using grow_array() vector to avoid memory corruption during metadata update processing.
8. mdadm: post metadata update to mdmon (mdmon is ready to receive it)
9. mdmon: process metadata update and calculate new array size. Store new array size with metadata update on disks.
... reshape ...
10. md : finishes reshape, array size is not increased by md as it is managed externally
11.mdmon: finishes migration in metadata
12.mdadm: reads array size from metadata and sets it to md
13.mdadm: For Raid0 array, execute takeover from Raid5 to Raid0
For IMSM, it is required to expand all arrays in container at time, so reshape has to be run on container and it is changed to serial execution for every array in container. Feature is treated as experimental due to Windows compatibility during reshape process, so last patch puts check to the code for EXPERIMENTAL compilation flag usage.
To use this feature 2 steps are required:
1. Add spares to container i.e. mdadm –add /dev/md/imsm_container_name /dev/sdX
For Raid0 spares are required also. Patch "[PATCH 17/23] Add spares to raid0 array using takeover" enables this.
2. Execute reshape i.e. : mdadm –grown /dev/md/imsm_container_name –raid-devices=requested_raid_disks_number –backup-file=patch_to_backup_file
Grow is executed for all arrays in container that command is executed on.
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Adam Kwolek (23):
imsm: Treat expansion as experimental feature
imsm: Add start limitation for container
imsm: Run Online Capacity Expansion on container
Finalize raid0 array expansion
Expand raid0 array using takeover
FIX: Raid0 takeover has to start monitoring Raid5
Add spares to raid0 array using takeover
Set size on reshape finish by mdadm
imsm: Set new array size in update_grow_array
imsm: Add support for finalize expansion in end_migration()
imsm: Add support for finalize expansion in imsm_set_disk()
imsm: Finalize reshape after adding disks to array
Finalize reshape after adding disks to array
imsm: FIX: core during imsm metadata writing
imsm: update metadata implementation for update_grow_array
imsm: FIX: crash on online capacity expansion start
Disable rebuild during Online Capacity Expansion
imsm: FIX: crash during reshape on recovery start update
imsm: Reconfigure mdmon, grow_array() implementation
Reconfigure mdmon on reshape start when disks number grows
imsm: update_super() implementation for adding disks
fix: mdadm memory corruption
Add Online Capacity Expansion to mdadm for external metadata
Grow.c | 642 ++++++++++++++++++++++++++++++++++++++++++++++-
Manage.c | 144 +++++++++++
managemon.c | 27 ++
mdadm.c | 2
mdadm.h | 39 +++
mdmon.h | 2
monitor.c | 76 ++----
super-intel.c | 771 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
sysfs.c | 142 ++++++++++
util.c | 95 +++++++
10 files changed, 1842 insertions(+), 98 deletions(-)
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