diff options
Diffstat (limited to 'md.4')
| -rw-r--r-- | md.4 | 16 |
1 files changed, 14 insertions, 2 deletions
@@ -526,10 +526,22 @@ Finally, "idle" can be written to stop the check/repair process. .B md/stripe_cache_size This is only available on RAID5 and RAID6. It records the size (in pages per device) of the stripe cache which is used for synchronising -all read and write operations to the array. The default is 128. +all write operations to the array and all read operations if the array +is degraded. The default is 256. Valid values are 17 to 32768. Increasing this number can increase performance in some situations, at -some cost in system memory. +some cost in system memory. Note, setting this value too high can +result in an "out of memory" condition for the system. +memory_consumed = system_page_size * nr_disks * stripe_cache_size + +.TP +.B md/preread_bypass_threshold +This is only available on RAID5 and RAID6. This variable sets the +number of times MD will service a full-stripe-write before servicing a +stripe that requires some "prereading". For fairness this defaults to +1. Valid values are 0 to stripe_cache_size. Setting this to 0 +maximizes sequential-write throughput at the cost of fairness to threads +doing small or random writes. .SS KERNEL PARAMETERS |