On Jun 9, 2016, at 10:45, Nathan Dauchy - NOAA Affiliate
wrote:
>
> Greetings All,
>
> After looking at this topic further, and discussions with a colleague at
> NASA, I could be convinced to be more aggressive in REstriping files wider
> with "lfs_migrate -A". I would like to know if anyone
Greetings All,
After looking at this topic further, and discussions with a colleague at
NASA, I could be convinced to be more aggressive in REstriping files wider
with "lfs_migrate -A". I would like to know if anyone has recent benchmark
results or analysis to support or refute the following...
Definitely the OST count is the upper limit on the stripe count. Fortunately,
that won't limit the file size to 100G x stripe_count. There _is_ a limit of
16TB per object for ldiskfs and 2^63 byte limit for ZFS (at least after LU-7890
is fixed).
Cheers, Andreas
On May 29, 2016, at 11:16, E.S.
After (finally) reading this interesting discussion I was left with one
question:
Some of the rules suggested above would imply quite a large amount of
stripes as files get truly big, isn't the (logical) upper limit on striping
the amount of OSTs you have in the system?
Striping more then the OST c
Andreas,
Thanks very much for your comments...
On Wed, May 18, 2016 at 1:30 PM, Dilger, Andreas
wrote:
>
> On 2016/05/18, 11:22, "Nathan Dauchy - NOAA Affiliate" <
> nathan.dau...@noaa.gov> wrote:
>
> I'm looking for your experience and perhaps some lively discussion
> regarding "best practices
> On May 19, 2016, at 12:46 PM, Nathan Dauchy - NOAA Affiliate
> wrote:
>
> Thanks for pointing out the approach of trying to keep a single file from
> using too much space on an OST. It looks like the Log2(size_in_GB) method I
> proposed works well up to a point, but breaks down in the capa
On Wed, May 18, 2016 at 2:04 PM, Mohr Jr, Richard Frank (Rick Mohr) <
rm...@utk.edu> wrote:
>
> 2) Use some sort of formula (like ORNL’s “file_size/100GB” or even your
> log function)
>
> Since I mainly care about striping for large files and I want the stripe
> count to increase as file size grow
Best regards, Alex.
From: lustre-discuss on behalf of
Patrick Farrell
Sent: Wednesday, May 18, 2016 2:22:11 PM
To: lustre-discuss@lists.lustre.org
Subject: Re: [lustre-discuss] stripe count recommendation, and proposal for
auto-stripe tool
Nathan,
This *is* excellent fodder fo
Ah, of course - We're only talking about restriping existing stuff.
Yes, that's just fine - No lock conflicts on reading. Looks good to me.
This is probably also something we'd want to allow via HSM. Not sure
how the current patches interact with that (haven't looked).
- Patrick
On 05/19/2
Patrick,
You bring up an interesting point on read vs. write performance. We can't
use lfs_migrate control the stripe count used for writes (obviously), so
that is left up to the application developer or at least the user to
intelligently place shared access files in a directory with wider
stripi
> On May 18, 2016, at 1:22 PM, Nathan Dauchy - NOAA Affiliate
> wrote:
>
> Since there is the "increased overhead" of striping, and weather applications
> do unfortunately write MANY tiny files, we usually keep the filesystem
> default stripe count at 1. Unfortunately, there are several user
Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Intel High Performance Data Division
On 2016/05/18, 11:22, "Nathan Dauchy - NOAA Affiliate"
mailto:nathan.dau...@noaa.gov>> wrote:
Greetings All,
I'm looking for your experience and perhaps some lively discussion regarding
"best pra
Nathan,
This *is* excellent fodder for discussion.
A few thoughts from a developer perspective. When you stripe a file to
multiple OSTs, you're spreading the data out across multiple targets,
which (to my mind) has two purposes:
1) More even space usage across OSTs (mostly relevant for *reall
Hi Nathan,
Although not useful short-term, there is a plan to address this issue
via feature "progressive file layout":
http://lustre.ornl.gov/ecosystem-2016/documents/tech/Mohr-UTK-PFL.pdf
Generally the more users, the more headache is file striping.
A possible hack is to:
1) set small default s
Greetings All,
I'm looking for your experience and perhaps some lively discussion
regarding "best practices" for choosing a file stripe count. The Lustre
manual has good tips on "Choosing a Stripe Size", and in practice the
default 1M rarely causes problems on our systems. Stripe Count on the oth
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