I ran strace just to determine what is called here. bash used
openat(,,O_WRONLY,O_CREAT|O_APPEND) to open the file and I thought
openat() might be the issue, so I wrote a simple program to test. Turns
out that it is the O_APPEND bit, with either open() or openat() that
causes the behavior.
On 4/29/24 10:21, [email protected] wrote:
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Today's Topics:
1. Re: [EXTERNAL] [BULK] Files created in append mode don't obey
directory default stripe count
(Vicker, Darby J. (JSC-EG111)[Jacobs Technology, Inc.])
----------------------------------------------------------------------
Message: 1
Date: Mon, 29 Apr 2024 15:21:06 +0000
From: "Vicker, Darby J. (JSC-EG111)[Jacobs Technology, Inc.]"
<[email protected]>
To: "Otto, Frank" <[email protected]>,
"[email protected]" <[email protected]>
Subject: Re: [lustre-discuss] [EXTERNAL] [BULK] Files created in
append mode don't obey directory default stripe count
Message-ID:
<dm6pr09mb4662e01cbdc1827f3d92c077e9...@dm6pr09mb4662.namprd09.prod.outlook.com>
Content-Type: text/plain; charset="windows-1252"
Wow, I would say that is definitely not expected. I can recreate this on both
of our LFS?s. One is community lustre 2.14, the other is a DDN Exascalar.
Shown below is our community lustre but we also have a 3-segment PFL on our
Exascalar and the behavor is the same there.
$ echo > aaa
$ echo >> bbb
$ lfs getstripe aaa bbb
aaa
lcm_layout_gen: 3
lcm_mirror_count: 1
lcm_entry_count: 3
lcme_id: 1
lcme_mirror_id: 0
lcme_flags: init
lcme_extent.e_start: 0
lcme_extent.e_end: 33554432
lmm_stripe_count: 1
lmm_stripe_size: 4194304
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: 6
lmm_objects:
- 0: { l_ost_idx: 6, l_fid: [0x100060000:0xace8112:0x0] }
lcme_id: 2
lcme_mirror_id: 0
lcme_flags: 0
lcme_extent.e_start: 33554432
lcme_extent.e_end: 10737418240
lmm_stripe_count: 4
lmm_stripe_size: 4194304
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: -1
lcme_id: 3
lcme_mirror_id: 0
lcme_flags: 0
lcme_extent.e_start: 10737418240
lcme_extent.e_end: EOF
lmm_stripe_count: 8
lmm_stripe_size: 4194304
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: -1
bbb
lmm_stripe_count: 1
lmm_stripe_size: 2097152
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: 3
obdidx objid objid
group
3 179773949 0xab721fd 0
From: lustre-discuss <[email protected]> on behalf of Otto,
Frank via lustre-discuss <[email protected]>
Date: Monday, April 29, 2024 at 8:33 AM
To: [email protected] <[email protected]>
Subject: [EXTERNAL] [BULK] [lustre-discuss] Files created in append mode don't
obey directory default stripe count
CAUTION: This email originated from outside of NASA. Please take care when clicking
links or opening attachments. Use the "Report Message" button to report
suspicious messages to the NASA SOC.
See subject. Is it a known issue? Is it expected? Easy to reproduce:
# lfs getstripe .
.
stripe_count: 4 stripe_size: 1048576 pattern: raid0 stripe_offset: -1
# echo > aaa
# echo >> bbb
# lfs getstripe .
.
stripe_count: 4 stripe_size: 1048576 pattern: raid0 stripe_offset: -1
./aaa
lmm_stripe_count: 4
lmm_stripe_size: 1048576
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: 0
obdidx objid objid group
0 2830 0xb0e 0
1 2894 0xb4e 0
2 2831 0xb0f 0
3 2895 0xb4f 0
./bbb
lmm_stripe_count: 1
lmm_stripe_size: 1048576
lmm_pattern: raid0
lmm_layout_gen: 0
lmm_stripe_offset: 4
obdidx objid objid group
4 2831 0xb0f 0
As you see, file "bbb" is created with stripe count 1 instead of 4.
Observed in Lustre 2.12.x and Lustre 2.15.4.
Thanks,
Frank
--
Dr. Frank Otto
Senior Research Infrastructure Developer
UCL Centre for Advanced Research Computing
Tel: 020 7679 1506
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