[lustre-discuss] Why reads are slower than writes on lustre file system?

Nagmat Nazarov nagmat at nevada.unr.edu
Mon Sep 27 16:30:22 PDT 2021

My backing file system is ldiskfs.
The storage hardware is HDD I guess(Since I am using emulab cloud storage)
I am doing buffered I/O.

On Mon, Sep 27, 2021 at 4:20 PM Patrick Farrell <pfarrell at ddn.com> wrote:

> It does depend on your storage hardware, but modern Lustre software is
> generally the same or faster for reads.
> What is your backing file system - ldiskfs or ZFS?  And what is the
> storage hardware?  And are you doing direct or buffered I/O?
> ------------------------------
> *From:* lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on
> behalf of Nagmat Nazarov <nagmat at nevada.unr.edu>
> *Sent:* Monday, September 27, 2021 5:57 PM
> *To:* lustre-discuss at lists.lustre.org <lustre-discuss at lists.lustre.org>
> *Subject:* [lustre-discuss] Why reads are slower than writes on lustre
> file system?
> Dear Engineers,
> I have started working on a lustre file system. I have done couple of
> experiments so far:
> On the first experiment I am writing 100 files each 10MB and the batch
> size is 4K. I got 107MB/s bandwidth.
> On the second experiment I am (writing 10 files each 10MB and reading 1 10
> MB file back) for 10 times.  Here also the average bandwidth is 106MB/s
> while  read average bandwidth is 59MB/s which is very weird I guess?
> My question is, generally on ext4 file systems read average bandwidth is
> faster that write average bandwidth, why is it 2 times slower on lustre
> file system. My ethernet speed is 1Gb/s.
> Kind regards
> Nagmat Nazarov
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