On Mon, 17 Jan 2011 11:52:09 +0000 "Kwolek, Adam" <adam.kwolek@xxxxxxxxx> wrote: > > > > -----Original Message----- > > From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid- > > owner@xxxxxxxxxxxxxxx] On Behalf Of NeilBrown > > Sent: Monday, January 17, 2011 2:31 AM > > To: Kwolek, Adam > > Cc: linux-raid@xxxxxxxxxxxxxxx; Williams, Dan J; Ciechanowski, Ed; > > Neubauer, Wojciech > > Subject: Re: [PATCH 0/6] OLCE raid5/0 (all arrays in container) > > > > On Thu, 13 Jan 2011 15:50:02 +0100 Adam Kwolek <adam.kwolek@xxxxxxxxx> > > wrote: > > > > > The following series adds possibility to reshape all (raid0/5) arrays > > in container for expansion feature. > > > The main problem resolved in this series is how initialize second > > (and next) raid0 reshapes for container reshape > > > executed as set of array reshapes. > > > > > > For i.e. second raid0 array mdmon should initialize metadata to let > > know to mdadm that there is something more to reshape. > > > But problem is what to do when mdmon is not loaded? (for first raid0 > > array this is not a problem, reshape_super() in mdadm updates > > metadata). > > > > > > this is resolved by allowing mdadm to know what was reshaped so far. > > This allows to reshape arrays that are not reshaped yet, > > > without update from mdmon. > > > > There certainly are some complexities with reshaping a container with 2 > > RAID0 > > arrays in it. However the approach you are taking seems too > > complicated. > > > > This is how I think the particular case of 2 RAID0 array would work. > > It > > should generalise neatly to all other combinations. > > > > 1/ mdadm decides to proceeds with the reshape, updates the metadata > > (because > > mdmon isn't running), converts the array to RAID4, starts mdmon and > > then > > lets the reshape for the first array proceed. > > > > 2/ when the reshape completes, mdmon will notice and will call > > imsm_progress_container_reshape which will update the metadata > > for the second array so that reshape appears to be active. > > For i.e. second raid5 it is ok. > This will never happened when second array is raid0, it is not monitored yet as arrays metadata are updated/monitored one by one. > This means that that mdmon cannot tell (via metadata) to mdadm that next raid0 array needs to be reshaped. > This information is used in container_content() before second takeover (in reshape_array()) is executed. When the reshape of the first array completes, imsm_set_array_state will call imsm_progress_container_reshape which will cause the second array to be marked as migrating. container_content will be able to see this and reshape_array will be called. It should all work. > > > > > 3/ mdadm will convert the raid4 back to raid0 and so mdmon will exit. > > > > 4/ mdadm calls container_content and finds that the second array needs > > to > > be reshaped. It converts the array to raid4 and starts mdmon. > > Then they oversee the reshape of the second array > > Metadata for second array is not updates by mdmon as we want "now" start mdmon for it. > Yes it will, it is updated at the same time that the previous array finished the reshape. NeilBrown > > > > 5/ when the reshape completes, mdadm converts the array back to RAID0 > > and > > mdmon exits. > > > > All done. > > > All looks ok, except "next/2nd" raid0 array is reshaped. At "previous/1st" reshape finish, it is not monitored yet, so mdmon can't update metadata, > before mdadm enters reshape_array() to execute takeover and then mdmon is started. > Decision to enter reshape_array() is made based on metadata (not updated). > > This is a reason why I'm using additional list for reshape decision. If mdmon doesn't make update for raid0 (not monitored) > Mdadm tries to run mdmon for it (in reshape_array()) and waits for metadata update and decision about reshape. > > Such implementation allows to follow directions for single reshape_super() call for container operation. > > BR > Adam > > > > > > > > This should avoid almost all special-casing. > > > > NeilBrown > > > > > > > > > > BR > > > Adam > > > > > > --- > > > > > > Adam Kwolek (6): > > > FIX: sync_completed == 0 causes reshape cancellation in > > metadata > > > FIX: mdadm hangs during reshape > > > FIX: mdadm throws coredump on exit in error case > > > FIX: reshape raid0 on second array > > > FIX: continue raid0 reshape > > > imsm: Update metadata for second array > > > > > > > > > Grow.c | 95 > > +++++++++++++++++++++++++++++++++++++++++++++++++++------ > > > monitor.c | 4 ++ > > > super-intel.c | 35 +++++++++++++++++++-- > > > 3 files changed, 120 insertions(+), 14 deletions(-) > > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-raid" > > in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
