bneradt commented on code in PR #10960:
URL: https://github.com/apache/trafficserver/pull/10960#discussion_r1443212011
##########
doc/admin-guide/files/records.yaml.en.rst:
##########
@@ -2488,6 +2488,29 @@ Cache Control
used from the asynchronous IO threads when IO finishes and the ``CacheVC``
lock or stripe lock is
required.
+.. ts::cv:: CONFIG proxy.config.cache.max_disk_errors INT 5
+
+ Cache disks sometimes fail due to hardware problems. |TS| keeps count of
+ the number of times it encounters I/O errors when accessing each cache disk.
+ If the number of errors on a disk reaches this setting, |TS| removes that
+ disk from the cache.
+
+ Note that the count of errors is kept in memory, and is reset to zero when
+ |TS| is restarted. By default, |TS| will not remember which cache disk has
+ been removed in this way when it restarts. If you wish to change this
behavior
+ and prevent known bad disks from re-joining the cache upon restart, change
+ the setting :ts:cv:`proxy.config.cache.persist_bad_disks`.
+
+.. ts::cv:: CONFIG proxy.config.cache.persist_bad_disks INT 0
+
+ When enabled (``1``), |TS| will remember which cache disks have been
+ marked as failed through :ts:cv:`proxy.config.cache.max_disk_errors`,
+ even after a restart. A list of known bad cache disks is written to
+ ``localstatedir/known_bad_disks``. If you replace the known bad disks,
+ delete this file so that |TS| will use it in the cache again.
+
+ When disabled (``0``), |TS| will ignore the ``known_bad_disks`` file.
+
Review Comment:
It's typical to say something explicit about the default for something like
this, like:
```
This feature is disabled by default.
```
##########
src/iocore/cache/Cache.cc:
##########
@@ -336,6 +344,15 @@ CacheProcessor::start_internal(int flags)
opts |= O_CREAT;
}
+ // Check if the disk is known to be bad
Review Comment:
nit: end with a period.
##########
src/iocore/cache/Cache.cc:
##########
@@ -336,6 +344,15 @@ CacheProcessor::start_internal(int flags)
opts |= O_CREAT;
}
+ // Check if the disk is known to be bad
+ if (cache_config_persist_bad_disks && !known_bad_disks.empty()) {
+ if (known_bad_disks.find(paths[gndisks]) != known_bad_disks.end()) {
+ Note("%s is a known bad disk. Skipping.", paths[gndisks]);
Review Comment:
Probably should be a warning.
##########
include/tscore/Filenames.h:
##########
@@ -47,6 +47,7 @@ namespace filename
// Various other file names
constexpr const char *RECORDS_STATS = "records.snap";
constexpr const char *HOST_RECORDS = "host_records.yaml";
+ constexpr const char *BAD_DISKS = "bad_disks";
Review Comment:
Probably good to add a `.txt` suffix. That can be helpful for some editors.
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