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openzfs / zfs

OpenZFS on Linux and FreeBSD
https://openzfs.github.io/openzfs-docs
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sync writes very slow despite presence of SLOG #2373

Closed dswartz closed 10 years ago

dswartz commented 10 years ago

Trimmed down from my post to zfs-discuss mailing list. Raid10 array on a JBOD chassis. Dataset shared to vsphere using NFS (and therefore forced sync mode). Got a good SLOG SSD (intel s3700). With this as a log device, over gigabit, I get 100 MB/sec read and only 13MB/sec using crystaldiskmark from a win7 virtual client. If I boot a latest and greatest omnios instead, on the same exact HW (literally using the same pool, dataset, etc), I get 90MB/sec. 'zfs iostat -v' does indicate writes to the SLOG, so I am at a loss as to what is wrong, but this makes ZoL unusable for this use case for me. I found issue #1012, but it isn't clear (to me at least) if this is the same thing.

behlendorf commented 10 years ago

@dswartz Support for AIO has now been merged in to master which should help your performance. If we need to make additional performance improvements let's open a new issue to track them.

dswartz commented 10 years ago

@dswartz Support for AIO has now been merged in to master which should help your performance. If we need to make additional performance improvements let's open a new issue to track them.

Cool!