Good evening to all, I'm looking at growing a RAID1 array from 40GB to 100GB. The array has a write-intent bitmap enabled, but an email from Neil in August suggests that I should disable the bitmap when growing the array. Here's a bit of the email Neil sent to the list: >We cannot currently change the size of a write-intent bitmap. >So if we change the size of an array which has such a bitmap, it >tries to set bits beyond the end of the bitmap. > >For now, simply reject any request to change the size of an array >which has a bitmap. mdadm can remove the bitmap and add a new >one after the array has changed size. > [snip...] A couple questions I have: 1) Does the superblock increase in size when the array is grown to make room for a larger bitmap? (This doesn't seem possible to me, particularly if using a v1.1 or v1.2 superblock). or... 2) Is the problem mentioned in Neil's email in regard to a "restructuring" of the bitmap to accommodate a larger array (i.e. We only have "x" amount of room on the superblock, so re-divide the array into chucks that we can fit into the superblock)? In my use case, the block devices that compose the RAID1 array are fibre channel SAN volumes. When I grow them to 100GB on the FC target, the additional 60GB is appended to the end of the exported block device. My out-of-sync data will still be present on the first 40GB. With this in mind (and the adage that patches are welcome), has there been any interest in being able to use a write-intent bitmap for this kind of use case? The benefit of this functionality would keep me from eating two _full_ re-syncs on the array when growing the block devices. Thanks in advance, Bryan
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