# Not able to run qiime dada2 denoise-paired on ec2 instance

**URL:** https://forum.qiime2.org/t/not-able-to-run-qiime-dada2-denoise-paired-on-ec2-instance/25960
**Category:** Technical Support
**Tags:** memory, dada2
**Created:** [March 29, 2023, 3:22am UTC](https://forum.qiime2.org/t/not-able-to-run-qiime-dada2-denoise-paired-on-ec2-instance/25960 "2023-03-29T03:22:39Z")
**Posts on this page:** 1
**Showing post:** 8

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### Author: ![gregcaporaso](https://forum.qiime2.org/user_avatar/forum.qiime2.org/gregcaporaso/32/17769_2.png) [@gregcaporaso](https://forum.qiime2.org/u/gregcaporaso)
#### Post date: [April 4, 2023, 8:48pm UTC](https://forum.qiime2.org/t/not-able-to-run-qiime-dada2-denoise-paired-on-ec2-instance/25960/8 "2023-04-04T20:48:47Z")

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Hi @danielavarelat,  
Glad to hear that you were able to get past the DADA2 step!

Memory issues when classifying with Silva is a known problem. Some relatively recent discussion of this, and tips, are consolidated in [this post](https://forum.qiime2.org/t/silva-classifier-run-out-of-memory/18396/2) by @Nicholas_Bokulich.

@Mehrbod_Estaki also suggested that filtering low abundance features might help at this stage. You could do that with [`qiime feature-table filter-features --p-min-samples 2 ...`](https://docs.qiime2.org/2023.2/plugins/available/feature-table/filter-features/) (to include only features/ASVs that are present in at least two samples). You would do that filtering on your feature table, and then filter the features from your `repseq.qza` file using [`qiime feature-table filter-seqs --i-table ...`](https://docs.qiime2.org/2023.2/plugins/available/feature-table/filter-seqs/). This type of filter can reduce the feature count by as much as half sometimes, which can help a bit with memory.

Another alternative would be to use a different reference database for classification, such as Greengenes2 (classifiers available [here](https://docs.qiime2.org/2023.2/data-resources/#taxonomy-classifiers-for-use-with-q2-feature-classifier)) or GTDB (see [here](https://forum.qiime2.org/t/how-to-train-a-gtdb-ssu-classifier-using-rescript/25725) for details on how to train one of those).

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