Hello everyone,
I am curious to know other people's experience with reading data straight from the underlying volume. According to the documentation it should be fine:
http://www.gluster.org/documentation/Technical_FAQ/
Can I directly access the data on the underlying storage volumes?
If you are just doing just read()/access()/stat() like operations, you should be fine. If you are not using any new features (like quota/geo-replication etc etc) then technically, you can modify (but surely not rename(2) and link(2)) the data inside.
Note that this is not tested as part of gluster’s release cycle and not recommended for production use.
The last sentence doesn't recommend it for production use. I was wondering if there's any other concern besides the fact that it's not tested as part of the release cycle or one could expect actual some problems with the data being read while doing so?
What I am interested is only read operations (readdir, stat, read data). All the write operations will continue going over the shared/mounted drive. So what I want to know is that the data that I am reading will be consistent with the rest of the bricks and not corrupted in any way.
The reason why I am looking into this is two-fold:
1. I have a lot of small files (hundreds of thousands) that need to be read and reread very frequently. Doing so directly from the underlying disk is way faster.
2. Once I've read them once both metadata and actual data is automatically cached in the OS filesystem cache, thus subsequent reads take almost no time since very few of those files actually change between reruns.
I run a three (or five) way mirror and nothing fancy (no geo and such) so if I could, I would prefer to read of the local disk but I want to be certain that those reads, in terms of correctness and consistency, will be equivalent to reading of the shared drive itself.
Thank you in advance for sharing your experience.
Regards,
-- Rumen Telbizov
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