On Mon, 19 Sep 2011 12:57:48 +0000 "Czarnowska, Anna" <anna.czarnowska@xxxxxxxxx> wrote: > The patch below makes a better decision as to the size of required reservation. I've applied this, thanks. NeilBrown > > > -----Original Message----- > > From: Williams, Dan J [mailto:dan.j.williams@xxxxxxxxx] > > Sent: Tuesday, September 06, 2011 10:43 PM > > To: NeilBrown > > Cc: linux-raid@xxxxxxxxxxxxxxx; Czarnowska, Anna; Labun, Marcin; > > Ciechanowski, Ed > > Subject: Re: [PATCH 5/9] imsm: fix reserved sectors for spares > > > > On Mon, Aug 29, 2011 at 7:20 PM, NeilBrown <neilb@xxxxxxx> wrote: > > >> Anna rightly points out that this could probably be safely made > > >> bigger. As it stands this applies to too broad an array of disks. > > I > > >> think a happy medium (until we can nail down the forward > > compatibility > > >> of older oroms, v8 in this case) is to detect the case where the > > disk > > >> is being activated for rebuild and if it is at least as large as one > > >> of the existing members truncate the reserved region to the same > > size > > >> as the other member. That way we are at least compatible with > > >> whatever agent created the array in the first instance. > > >> > > > > > > I think you are saying that I can go ahead and apply this patch, but > > that it > > > might get improved upon in the future .... I hope that is right ? > > > > Yes, this may have corrected things too far in the other direction, > > but is less surprising than what we had before. > > >From bf5c919219d9947a0eba1ce2b450c8f663291f48 Mon Sep 17 00:00:00 2001 > From: Anna Czarnowska <anna.czarnowska@xxxxxxxxx> > Date: Mon, 19 Sep 2011 13:41:46 +0200 > Subject: [PATCH] Calculate reservation for a spare based on active disks in container > > New function to calculate minimum reservation to expect from a spare > is introduced. > > The required amount of space at the end of the disk depends on what we > plan to do with the spare and what array we want to use it in. > For creating new subarray in an empty container the full reservation of > MPB_SECTOR_COUNT + IMSM_RESERVED_SECTORS is required. > > For recovery or OLCE on a volume using new metadata format at least > MPB_SECTOR_CNT + NUM_BLOCKS_DIRTY_STRIPE_REGION is required. > The additional space for migration optimization included in > IMSM_RESERVED_SECTORS is not necessary and is not reserved by some oroms. > > MPB_SECTOR_CNT alone is not sufficient as it does not include the > reservation at the end of subarray. > > However if the real reservation on active disks is smaller than this > (when the array uses old metadata format) we should use the real value. > This will allow OLCE and recovery to start on the spare even if the volume > doesn't have the reservation we normally use for new volumes. > > Signed-off-by: Anna Czarnowska <anna.czarnowska@xxxxxxxxx> > --- > super-intel.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-- > 1 files changed, 54 insertions(+), 2 deletions(-) > > diff --git a/super-intel.c b/super-intel.c > index f1c924f..8dad03c 100644 > --- a/super-intel.c > +++ b/super-intel.c > @@ -88,6 +88,7 @@ > > #define MPB_SECTOR_CNT 2210 > #define IMSM_RESERVED_SECTORS 4096 > +#define NUM_BLOCKS_DIRTY_STRIPE_REGION 2056 > #define SECT_PER_MB_SHIFT 11 > > /* Disk configuration info. */ > @@ -827,6 +828,8 @@ static int count_memberships(struct dl *dl, struct intel_super *super) > return memberships; > } > > +static __u32 imsm_min_reserved_sectors(struct intel_super *super); > + > static struct extent *get_extents(struct intel_super *super, struct dl *dl) > { > /* find a list of used extents on the given physical device */ > @@ -840,7 +843,7 @@ static struct extent *get_extents(struct intel_super *super, struct dl *dl) > * IMSM_RESERVED_SECTORS region > */ > if (dl->index == -1) > - reservation = MPB_SECTOR_CNT; > + reservation = imsm_min_reserved_sectors(super); > else > reservation = MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS; > > @@ -933,6 +936,51 @@ static int is_failed(struct imsm_disk *disk) > return (disk->status & FAILED_DISK) == FAILED_DISK; > } > > +/* try to determine how much space is reserved for metadata from > + * the last get_extents() entry on the smallest active disk, > + * otherwise fallback to the default > + */ > +static __u32 imsm_min_reserved_sectors(struct intel_super *super) > +{ > + struct extent *e; > + int i; > + __u32 min_active, remainder; > + __u32 rv = MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS; > + struct dl *dl, *dl_min = NULL; > + > + if (!super) > + return rv; > + > + min_active = 0; > + for (dl = super->disks; dl; dl = dl->next) { > + if (dl->index < 0) > + continue; > + if (dl->disk.total_blocks < min_active || min_active == 0) { > + dl_min = dl; > + min_active = dl->disk.total_blocks; > + } > + } > + if (!dl_min) > + return rv; > + > + /* find last lba used by subarrays on the smallest active disk */ > + e = get_extents(super, dl_min); > + if (!e) > + return rv; > + for (i = 0; e[i].size; i++) > + continue; > + > + remainder = min_active - e[i].start; > + free(e); > + > + /* to give priority to recovery we should not require full > + IMSM_RESERVED_SECTORS from the spare */ > + rv = MPB_SECTOR_CNT + NUM_BLOCKS_DIRTY_STRIPE_REGION; > + > + /* if real reservation is smaller use that value */ > + return (remainder < rv) ? remainder : rv; > +} > + > /* Return minimum size of a spare that can be used in this array*/ > static unsigned long long min_acceptable_spare_size_imsm(struct supertype *st) > { > @@ -941,6 +989,7 @@ static unsigned long long min_acceptable_spare_size_imsm(struct supertype *st) > struct extent *e; > int i; > unsigned long long rv = 0; > + __u32 reservation; > > if (!super) > return rv; > @@ -958,9 +1007,12 @@ static unsigned long long min_acceptable_spare_size_imsm(struct supertype *st) > continue; > if (i > 0) > rv = e[i-1].start + e[i-1].size; > + reservation = __le32_to_cpu(dl->disk.total_blocks) - e[i].start; > free(e); > + > /* add the amount of space needed for metadata */ > - rv = rv + MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS; > + rv = rv + imsm_min_reserved_sectors(super); > + > return rv * 512; > } >
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