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Tests for reading around a member much slower than the rest of its stripe: a read of its data is reconstructed from the stripe's other blocks when its latency estimate says that's faster. Five or six 1G members, 3+1 stripes unless noted, and a dm-delay member at 500 ms. - ec_read_slow_device: reads of the slow member's data don't wait for it. - ec_read_healthy, ec_read_around_disabled: no read-arounds on a healthy pool, or with ec_read_around_penalty=0. - ec_read_around_pq: 4+2 stripes with two slow members. - ec_read_around_fallback, _fallback_reconstruct: a read-around that reads a bad block falls back to the member, then to the full reconstruct. - ec_read_around_small_extents, ec_read_around_nocsum: read amplification with 4k extents, and unchecksummed data. - ec_repair_reads_around_slow_device, ec_reconcile_reads_around_slow_device: evacuation and reconcile rebuild a slow member's blocks from the rest of the stripe. - ec_reconcile_learns_failing_device, ec_evacuate_learns_failing_device: from a cold estimate, with a member at 7 s per read, reconcile's and evacuation's own reads bring its estimate up. - ec_reconstruct_skips_failed_block: a reconstruct after a read error doesn't read the failed block again. Tests with a delayed member warm its estimate first with random reads, read-around off. Needs the read-around series. Replaces koverstreet#130, whose tests asserted that an evacuating device is never read.
This was referenced Oct 5, 2026
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With a promote target, a read-around promotes as a direct read does, so a second read of a slow member's data comes from the promote target. Five members in group hdd, two behind dm-delay, and a promote target in group ssd, set only after the setup's reads and the prewarm. The first pass reads around; the second must not read around at all, and must read most of the file from the promote target. ec_ra_setup takes per-device labels from ec_ra_labels. Needs the read-around series with "ec: promote read-around results".
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Pushed a second commit, ec_read_around_promotes, for the promote commit added to koverstreet/bcachefs-tools#1098. The first commit is unchanged; the description has an update at the end. |
This was referenced Oct 5, 2026
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Replaces #130. Tests for EC read-around (koverstreet/bcachefs-tools#1071):
a read of data on a member much slower than the rest of its stripe is
reconstructed from the stripe's other blocks when the latency estimates say
that's faster.
#130 asserted that an evacuating device is never read. What matters is
latency, so these test the latency rule: plain reads, P+Q, the fallbacks,
evacuate and reconcile around a slow member, and cold estimates with a
member at 7 s per read.
They need the read-around series (koverstreet/bcachefs-tools#1098), so they fail
on testing until it lands. With it, on testing 7feb652c2, all 13 pass.
Update 2026-10-05: added a second commit, ec_read_around_promotes: with a promote target, a second read of a slow member's data must come from the promote target. ec_ra_setup now takes optional per-device labels, for the promote target. It needs the new last commit of bcachefs-tools#1098. On testing 8e6613cec, all 14 tests pass with the series; without that commit, ec_read_around_promotes fails (78 read-arounds in the second pass).