[lustre-discuss] default directory striping with Lustre 2.8

[Faaland, Olaf P.]

Hello Juan,

No, I haven't seen the problem you describe.  Our testing configuration has only a single target per server - each MDS has a single MDT, and each OSS has a single OST.

We've encountered some issues, but so far stability has been good.  Our testing has been on relatively small scale, though.

Olaf P. Faaland
Livermore Computing

________________________________________
From: Juan PC [piernas at ditec.um.es]
Sent: Monday, May 09, 2016 4:25 AM
To: Faaland, Olaf P.; lustre-discuss at lists.lustre.org
Subject: Re: [lustre-discuss] default directory striping with Lustre 2.8

Dear Olaf,

I would like to hear about your experience with stripped directories in
Lustre 2.8. Mine is that this feature is still unstable and a lot of
"BUG: soft lockup..." errors start appearing. Maybe the problem is the
setup that I use: as many OSTs as MDTs, with a pair OST-MDT per server.

Have you faced the same problem?

Regards,

        Juan


El 05/05/16 a las 01:04, Faaland, Olaf P. escribió:
> Hi,
>
> Suppose you have m MDTs in your filesystem, and create a new directory
> and set default directory striping using
>
> lfs mkdir --count=c --index=k <path> && lfs setdirstripe --default
> --count=c <path>
>
> Suppose that c < m and m > 2.
>
> Then you make subdirectories, like
>
> mkdir <path>/child.{1,2,3,...}
>
> a) By design, do the child directories have the same starting index as
> <path>?
> b) By design, are the child directories all striped across the same set
> of MDTs as <path>?
>
> I didn't see that specified one way or the other in the DNE phase 2 high
> level design document at
> http://wiki.opensfs.org/DNE_StripedDirectories_HighLevelDesign_wiki_version.
> If I should look elsewhere, let me know.
>
> In a test I was doing today, I noticed that neither (a) nor (b) were
> true in practice.  I'm wondering whether that's a bug or a feature.
> Here's partial output from my test.
>
> $ lfs mkdir --count=6 --index=2 /p/lustre/faaland1/count6_index2
> $ lfs setdirstripe -D --count=6 /p/lustre/faaland1/count6_index2
> $ mkdir
> /p/lustre/faaland1/count6_index2/subdir.{1,2,3,4,5,6,7,8,9,10,11,12,13,14}
> $ lfs getdirstripe /p/lustre/faaland1/count6_index2
> /p/lustre/faaland1/count6_index2
> lmv_stripe_count: 6 lmv_stripe_offset: 2
> mdtidx           FID[seq:oid:ver]
>      2           [0x280000400:0x33f3:0x0]
>      3           [0x2c0000404:0x33f3:0x0]
>      4           [0x300000402:0x33f2:0x0]
>      5           [0x340000407:0x33f1:0x0]
>      6           [0x380000406:0x33f0:0x0]
>      7           [0x3c0000404:0x33ef:0x0]
> /p/lustre/faaland1/count6_index2/subdir.4
> lmv_stripe_count: 6 lmv_stripe_offset: 2
> mdtidx           FID[seq:oid:ver]
>      2           [0x280000400:0x33f5:0x0]
>      3           [0x2c0000404:0x33f5:0x0]
>      4           [0x300000402:0x33f4:0x0]
>      5           [0x340000407:0x33f3:0x0]
>      6           [0x380000406:0x33f2:0x0]
>      7           [0x3c0000404:0x33f1:0x0]
> /p/lustre/faaland1/count6_index2/subdir.9
> lmv_stripe_count: 6 lmv_stripe_offset: 5
> mdtidx           FID[seq:oid:ver]
>      5           [0x340000400:0x37a1:0x0]
>      6           [0x380000405:0x37a1:0x0]
>      7           [0x3c0000402:0x37a0:0x0]
>      8           [0x40000040e:0x379f:0x0]
>      9           [0x440000403:0x379e:0x0]
>      0           [0x200000405:0x379d:0x0]
> /p/lustre/faaland1/count6_index2/subdir.3
> lmv_stripe_count: 6 lmv_stripe_offset: 5
> mdtidx           FID[seq:oid:ver]
>      5           [0x340000400:0x37a0:0x0]
>      6           [0x380000405:0x37a0:0x0]
>      7           [0x3c0000402:0x379f:0x0]
>      8           [0x40000040e:0x379e:0x0]
>      9           [0x440000403:0x379d:0x0]
>      0           [0x200000405:0x379c:0x0]
> /p/lustre/faaland1/count6_index2/subdir.14
> lmv_stripe_count: 6 lmv_stripe_offset: 7
> mdtidx           FID[seq:oid:ver]
>      7           [0x3c0000400:0x30d4:0x0]
>      8           [0x400000403:0x30d4:0x0]
>      9           [0x440000405:0x30d3:0x0]
>      0           [0x200000407:0x30d2:0x0]
>      1           [0x240000407:0x30d1:0x0]
>      2           [0x280000407:0x30d0:0x0]
> ...
>
>
> Olaf P. Faaland
> Livermore Computing
> phone : 925-422-2263
>
>
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--
D. Juan Piernas Cánovas
Departamento de Ingeniería y Tecnología de Computadores
Facultad de Informática. Universidad de Murcia
Campus de Espinardo - 30080 Murcia (SPAIN)
Tel.: +34868887657    Fax: +34868884151
email: piernas at ditec.um.es
PGP public key:
http://pgp.rediris.es:11371/pks/lookup?search=piernas%40ditec.um.es&op=index

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