All Posts by Date or last 15, 30, 90 or 180 days.
also by Lloyd: diglloyd.com photography and WindInMyFace.com

Thank you for buying via links and ads on this site,
which earn me advertising fees or commissions.
As an Amazon Associate I earn from qualifying purchases.

Other World Computing...
B&H Photo...
Amazon
As an Amazon Associate I earn from qualifying purchases.
Up to 1527MB/s sustained performance
877-865-7002
Today’s Deal Zone Items... Handpicked deals...
$1100 $880
SAVE $220

$999 $779
SAVE $220

$1299 $949
SAVE $350

$799 $549
SAVE $250

$1499 $999
SAVE $500

$799 $549
SAVE $250

$2797 $2497
SAVE $300

$1997 $1797
SAVE $200

$549 $499
SAVE $50

$1699 $949
SAVE $750

$240 $175
SAVE $65

$3399 $2699
SAVE $700

diglloydTools MemoryTester Finds Bad Memory in Server Today

diglloydTools includes IntegrityChecker for data integrity (including a cross-platform Java version that works on Mac, Windows, Linux, etc), and MemoryTester and DiskTester.

I have new respect for my own testing tool! My diglloydTools MemoryTester has always been 'boring' with memory free issues, in that it is a good tool for proving real-world memory bandwidth. But today it confirmed bad memory modules were in fact the problem.

Today’s afternoon in a data center fixing my web server turned out to be bad memory modules, which diglloydTools MemoryTester found instantly. Having run 24X7 for some years, they started failing a month or so ago, with sporadic warning signs including:

  • macOS El Capitan sporadically crashing with a panic twice a week or so.
  • Java Virtual Machine (JVM) randomly once a day, from an internal memory check.
  • Source code versioning software 'git' failing 'git gc' and 'git fsck' with corruption/hashing errors. And the apparently corrupted index file from last week.
  • Random reports of file corruption by IntegrityChecker Java (files randomly fail to validate, not consistent).
OWC memory modules
failed after ~9 years of use including ~4 years of 24X7 server use
OWC replaced the modules — lifetime warranty

Instant and correct diagnosis

But diglloydTools MemoryTester can be run at any time without special protocols. But all eight test threads found the bad memory problems within a few seconds.

diglloydWeb:WIND lloyd$ mt stress
MemoryTester 1.6.1 64-bit, diglloydTools 2.2.15, 2017-12-24 18:12
Copyright 2006-2017 DIGLLOYD INC. All Rights Reserved
Use of this software requires a license. See http://macperformanceguide.com/Software-License.html
OS X 10.11.6, 8 CPU cores @ 2300 MHz, 16384 MiB memory
Monday, October 11, 2021 at 2:26:38 PM Pacific Daylight Time
********************************** Stress Test *********************************
Test duration: 8h
CPU percent: 100% per cpu core
Num CPU threads: 8
Memory per thread (requested): 1.79 GiB
...
Speeds denote memory bandwidth: copy and compare speed (memcpy + 64-bit compare)
Allow several minutes for averages to stabilize, especially with large memory sizes.
Task EatCPU-5 exited with error: -1, msg ="BAD MEMORY, changed after copy!"
6s:  7160  1432 1432 1432 1432 1432    0    0    0 (best)
10s: 10492  1749 1749 1749 1749 1749    0 1749    0 (best)
Task EatCPU-3 exited with error: -1, msg ="BAD MEMORY, changed after copy!"
16s: 11586  2207 2207 1655 1655 2207    0 1655    0 (best)
20s: 12398  2214 2214 1771 1328 2214    0 2214  443 (best)
Task EatCPU-4 exited with error: -1, msg ="BAD MEMORY, changed after copy!"
Task EatCPU-2 exited with error: -1, msg ="BAD MEMORY, changed after copy!"
26s: 13320  2391 2391 2049 1025 2049    0 2391 1025 (best)
30s: 13338  2668 2371 1778  889 1778    0 2371 1482 (best)
36s: 13849  2721 2721 1484  742 1484    0 2721 1979 (best)
40s: 14033  2896 2896 1337  668 1337    0 2896 2005 (best)
Task EatCPU-6 exited with error: -1, msg ="BAD MEMORY, changed after copy!"
46s: 14344  3102 3102 1163  582 1163    0 2714 2520 (best)
50s: 14451  3390 3212 1071  535 1071    0 2498 2676 (best)
Task EatCPU-1 exited with error: -1, msg ="BAD MEMORY, changed after copy!"
56s: 14662  3825 3028  956  478  956    0 2231 3188 (best)
60s: 14582  4018 2827  893  446  893    0 2083 3422
Task EatCPU-7 exited with error: -1, msg ="BAD MEMORY, changed after copy!"
Task EatCPU-0 exited with error: -1, msg ="BAD MEMORY, changed after copy!"
66s: 14073  4060 2571  812  406  812    0 1894 3518

Verification of smooth operation after memory swapped-out

No problem with the swapped-out memory.

diglloydWeb:WIND lloyd$ mt stress
diglloydWeb:MPG lloyd$ mt stress -m 500M
MemoryTester 1.6.1 64-bit, diglloydTools 2.2.15, 2017-12-24 18:12
Copyright 2006-2017 DIGLLOYD INC. All Rights Reserved
Use of this software requires a license. See http://macperformanceguide.com/Software-License.html
OS X 10.11.6, 8 CPU cores @ 2300 MHz, 16384 MiB memory
Monday, October 11, 2021 at 3:18:44 PM Pacific Daylight Time
********************************** Stress Test *********************************
Test duration: 8h
CPU percent: 100% per cpu core
Num CPU threads: 8
Memory per thread (requested): 500 MiB
...
=====> Use ctrl-C to stop <=====
Speeds denote memory bandwidth: copy and compare speed (memcpy + 64-bit compare)
Allow several minutes for averages to stabilize, especially with large memory sizes.
6s:  9588   400  400  400  400  400 2797 2397 2397 (best)
10s:  9991   731  731  731  731  731 2437 1950 1950 (best)
16s:  9993   922  922  922  922  922 1999 1691 1691 (best)
20s:  9994   987  987  987  987  987 1851 1604 1604 (best)
26s: 10276  1047 1047 1047 1047 1047 1808 1618 1618 (best)
30s: 10239  1073 1073 1073 1073 1073 1734 1569 1569
36s: 10541  1171 1171 1171 1171 1171 1654 1516 1516 (best)
40s: 10487  1179 1179 1179 1179 1179 1613 1489 1489
46s: 10531  1188 1188 1188 1188 1188 1620 1458 1512
50s: 10539  1193 1193 1193 1193 1193 1591 1491 1491
56s: 10481  1199 1199 1199 1199 1199 1554 1466 1466
60s: 10614  1202 1244 1244 1244 1244 1534 1451 1451 (best)
66s: 10671  1244 1244 1244 1244 1244 1508 1471 1471 (best)
70s: 10632  1245 1245 1245 1245 1245 1494 1458 1458
76s: 10746  1278 1278 1278 1278 1245 1507 1442 1442 (best)
80s: 10740  1276 1276 1276 1276 1276 1494 1432 1432
86s: 10745  1274 1274 1274 1274 1274 1477 1448 1448
90s: 10851  1301 1273 1301 1301 1301 1495 1439 1439 (best)
96s: 10849  1298 1298 1298 1298 1298 1479 1454 1428
100s: 10815  1296 1296 1296 1296 1296 1470 1445 1420
106s: 10839  1317 1293 1293 1293 1293 1481 1434 1434
110s: 10854  1314 1292 1314 1314 1292 1473 1428 1428 (best)
116s: 10853  1311 1289 1311 1311 1311 1461 1440 1418
120s: 10844  1309 1309 1309 1309 1309 1454 1433 1413
126s: 10804  1306 1306 1306 1306 1306 1445 1425 1405
130s: 10779  1304 1304 1304 1304 1304 1439 1419 1400
136s: 10781  1302 1302 1320 1302 1302 1430 1412 1412
140s: 10794  1318 1300 1318 1318 1300 1425 1407 1407
146s: 10795  1315 1298 1315 1315 1315 1435 1401 1401
150s: 10774  1314 1297 1314 1314 1314 1430 1397 1397
...
View all handpicked deals...

Apple 13.3" MacBook Air with Retina Display (Early 2020, Gold)
$999 $779
SAVE $220

diglloyd.com | Terms of Use | PRIVACY POLICY
Contact | About Lloyd Chambers | Consulting | Photo Tours
Mailing Lists | RSS Feeds | Twitter
Copyright © 2020 diglloyd Inc, all rights reserved.
Display info: __RETINA_INFO_STATUS__