Hi, Gregory!
Thanks for the comment. I compiled simple program to play with write speed measurements (from librados examples). Underline "write" functions are:
rados_write(io, "hw", read_res, 1048576, i*1048576);
rados_aio_write(io, "foo", comp, read_res, 1048576, i*1048576);
So I consecutively put 1MB blocks on CEPH. What I measured is that rados_aio_write gives me about 5 times the speed of rados_write. I make 128 consecutive writes in for loop to create object of maximum allowed size of 132MB.
Now if I do consecutive write from some client into CEPH storage, then what is the recommended buffer size? (I'm trying to debug very poor Bareos write speed of just 3MB/s to CEPH)
Thank you,
Alexander
On Fri, Sep 29, 2017 at 5:18 PM, Gregory Farnum <gfarnum@xxxxxxxxxx> wrote:
It sounds like you are doing synchronous reads of small objects here. In that case you are dominated by the per-op already rather than the throughout of your cluster. Using aio or multiple threads will let you parallelism requests.
-GregOn Fri, Sep 29, 2017 at 3:33 AM Alexander Kushnirenko <kushnirenko@xxxxxxxxx> wrote:______________________________Hello,We see very poor performance when reading/writing rados objects. The speed is only 3-4MB/sec, compared to 95MB rados benchmarking.When you look on underline code it uses librados and linradosstripper libraries (both have poor performance) and the code uses rados_read and rados_write functions. If you look on examples they recommend rados_aio_read/write.Could this be the reason for poor performance?Thank you,Alexander._________________
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