From 9860101b701fa9e48b23254f06a0a7080ee91e19 Mon Sep 17 00:00:00 2001 From: Josh Moore Date: Thu, 22 Aug 2024 14:17:48 +0200 Subject: [PATCH] Update chunks/shards text --- README.md | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/README.md b/README.md index ee29ff2..06e37d1 100644 --- a/README.md +++ b/README.md @@ -281,10 +281,18 @@ export PATH=$PATH:$HOME/.cargo/bin #### Optimizing chunks and shards -Finally, there is not yet a single heuristic for determining the chunk and shard -sizes that will work for all data. Pass the `--output-chunks` and -`--output-shards` flags in order to set the size of chunks and shards for all -resolutions: +Zarr v3 supports shards, which are files that contain multiple chunks. The shape +of a shard must be a multiple of the chunk size in every dimension. There is not +yet a single heuristic for determining the chunk and shard sizes that will work +for all data. **The default shard shape chosen by resave is the full shape of +the image array.** + +In order to limit the size of a shard, if the shard exceeds 100,000,000 pixels +then you must specify the shard-shape. You can specify the shard shape, using +--output-shards, which will be used for all pyramid resolutions. This may cause +issues if the chunk shape changes for lower resolutions (to match the smaller +image shape). In this case, you should also specify the chunk-shape to be used +for all resolutions: ``` ome2024-ngff-challenge resave --cc-by input.zarr output.zarr --output-chunks=1,1,1,256,256 --output-shards=1,1,1,2048,2048