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- May 19, 2017
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I've been doing some more testing and the evidence suggests that using a L2ARC with a metadata only flag has a potential substantial positive impact on rsync performance over AFP. For largely dormant data, the combination of L2ARC dedicated to metadata seems to benefit rsync performance a lot.
For example, I ran rsync on a 1.15TB iTunes folder with 30k+ music files, assorted images, iOS apps, etc. and the rsync completed in 5 minutes over a 10 GBe connection. 1.5GB of newly-added songs was also copied to an external RAID5 array. Previously, this task would take 40+ minutes.
Granted, my new server has a more powerful CPU, but I'd wager that the spinning storage is the bottleneck here, esp. for small files like all the iOS stuff still stored in my iTunes folder. I also find browsing the various directories to be much quicker now. It's almost like DAS.
Thus, folk with similar use cases may want to consider experimentally adding a L2ARC with the metadata only flag even if their FreeNAS doesn't have 64GB of RAM, etc. However, to fill the L2ARC with metadata, you will have to run the rsync a couple of times to fill it - each rsync should decrease in time as the L2ARC fills with metadata.
For example, I ran rsync on a 1.15TB iTunes folder with 30k+ music files, assorted images, iOS apps, etc. and the rsync completed in 5 minutes over a 10 GBe connection. 1.5GB of newly-added songs was also copied to an external RAID5 array. Previously, this task would take 40+ minutes.
Granted, my new server has a more powerful CPU, but I'd wager that the spinning storage is the bottleneck here, esp. for small files like all the iOS stuff still stored in my iTunes folder. I also find browsing the various directories to be much quicker now. It's almost like DAS.
Thus, folk with similar use cases may want to consider experimentally adding a L2ARC with the metadata only flag even if their FreeNAS doesn't have 64GB of RAM, etc. However, to fill the L2ARC with metadata, you will have to run the rsync a couple of times to fill it - each rsync should decrease in time as the L2ARC fills with metadata.