[lustre-discuss] What happens if my stripe count is set to more than my number of stripes

[Prakrati.Agrawal at shell.com]

Hi,

To be precise,
File size = 64 GB
Stripe size = 1 GB
Stripe count = 128
But since I have 64 ranks, each rank will write 1 GB on 1 OST till 64 OSTs but what happens to the rest of the 64 OSTs.
Please let me know what happens in this case?

Thanks and Regards,
Prakrati


From: Ben Evans [mailto:Ben.Evans at terascala.com]
Sent: Monday, April 20, 2015 7:24 PM
To: Agrawal, Prakrati PTIN-PTT/ICOE; lustre-discuss at lists.lustre.org
Subject: Re: [lustre-discuss] What happens if my stripe count is set to more than my number of stripes


When you set striping, you set the number of OSTs you would like to use, say for your example, you chose 4.



The way the file would be striped is that the first GB would be written to OST 1, the second GB would be written to OST 2, etc.



The 5th GB is written to OST 1 again, etc.



If you set your stripe size to 128GB, and write 64 GB, you will have written 64GB to OST 1, but nothing to OSTs 2-4.



I hope this answered your question.



-Ben Evans



________________________________
From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org<mailto:lustre-discuss-bounces at lists.lustre.org>> on behalf of Prakrati.Agrawal at shell.com<mailto:Prakrati.Agrawal at shell.com> <Prakrati.Agrawal at shell.com<mailto:Prakrati.Agrawal at shell.com>>
Sent: Monday, April 20, 2015 4:47 AM
To: lustre-discuss at lists.lustre.org<mailto:lustre-discuss at lists.lustre.org>
Subject: [lustre-discuss] What happens if my stripe count is set to more than my number of stripes

Hi,

I have a doubt regarding Lustre file system. If I have a file of size 64 GB and I set stripe size to 1GB, my number of stripes become 64. But if I set my stripe count as 128, what does the Lustre do in that case?

Thanks and Regards,
Prakrati
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