The main goal of this PR is to solve the situation where disks stop
responding to operations. This generally causes an FD build-up and
eventually will crash the server.
This adds detection of hung disks, where calls on disk get stuck.
We add functionality to `xlStorageDiskIDCheck` where it keeps
track of the number of concurrent requests on a given disk.
A total number of 100 operations are allowed. If this limit is reached
we will block (but not reject) new requests, but we will monitor the
state of the disk.
If no requests have been completed or updated within a 15-second
window, we mark the disk as offline. Requests that are blocked will be
unblocked and return an error as "faulty disk".
New requests will be rejected until the disk is marked OK again.
Once a disk has been marked faulty, a check will run every 5 seconds that
will attempt to write and read back a file. As long as this fails the disk will
remain faulty.
To prevent lots of long-running requests to mark the disk faulty we
implement a callback feature that allows updating the status as parts
of these operations are running.
We add a reader and writer wrapper that will update the status of each
successful read/write operation. This should allow fine enough granularity
that a slow, but still operational disk will not reach 15 seconds where
50 operations have not progressed.
Note that errors themselves are not enough to mark a disk faulty.
A nil (or io.EOF) error will mark a disk as "good".
* Make concurrent disk setting configurable via `_MINIO_DISK_MAX_CONCURRENT`.
* de-couple IsOnline() from disk health tracker
The purpose of IsOnline() is to ensure that we
reconnect the drive only when the "drive" was
- disconnected from network we need to validate
if the drive is "correct" and is the same drive
which belongs to this server.
- drive was replaced we have to format it - we
support hot swapping of the drives.
IsOnline() is not meant for taking the drive offline
when it is hung, it is not useful we can let the
drive be online instead "return" errors for relevant
calls.
* return errFaultyDisk for DiskInfo() call
Co-authored-by: Harshavardhana <harsha@minio.io>
Possible future Improvements:
* Unify the REST server and local xlStorageDiskIDCheck. This would also improve stats significantly.
* Allow reads/writes to be aborted by the context.
* Add usage stats, concurrent count, blocked operations, etc.
This speed-up is intended for faster startup times
for almost all MinIO operations. Changes here are
- Drives are not re-read for 'format.json' on a regular
basis once read during init is remembered and refreshed
at 5 second intervals.
- Do not do O_DIRECT tests on drives with existing 'format.json'
only fresh setups need this check.
- Parallelize initializing erasureSets for multiple sets.
- Avoid re-reading format.json when migrating 'format.json'
from really old V1->V2->V3
- Keep a copy of local drives for any given server in memory
for a quick lookup.
- remove some duplicated code
- reported a bug, separately fixed in #13664
- using strings.ReplaceAll() when needed
- using filepath.ToSlash() use when needed
- remove all non-Go style comments from the codebase
Co-authored-by: Aditya Manthramurthy <donatello@users.noreply.github.com>
Borrowed idea from Go's usage of this
optimization for ReadFrom() on client
side, we should re-use the 32k buffers
io.Copy() allocates for generic copy
from a reader to writer.
the performance increase for reads for
really tiny objects is at this range
after this change.
> * Fastest: +7.89% (+1.3 MiB/s) throughput, +7.89% (+1308.1) obj/s
This PR brings two optimizations mainly
for page-cache build-up and how to avoid
getting OOM killed in the process. Although
these memories are reclaimable Linux is not
fast enough to reclaim them as needed on a
very busy system. fadvise is a system call
implemented in Linux to advise page-cache to
avoid overload as we get significant amount
of requests on the server.
- FADV_SEQUENTIAL tells that all I/O from now
is going to be sequential, allowing for more
resposive throughput.
- FADV_NOREUSE tells kernel to start removing
things for this 'fd' from page-cache.
Use a single allocation for reading the file, not the growing buffer of `io.ReadAll`.
Reuse the write buffer if we can when writing metadata in RenameData.
This is to ensure that there are no projects
that try to import `minio/minio/pkg` into
their own repo. Any such common packages should
go to `https://github.com/minio/pkg`
Klaus Post
Harshavardhana