title_wip

### BlockDiscardTime\_*name*[​](#blockdiscardtime_name "Direct link to blockdiscardtime_name")

Time in seconds spend in discard operations requested from the block device, summed across all the operations. These operations are relevant for SSD. Discard operations are not used by ClickHouse, but can be used by other processes on the system. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockInFlightOps\_*name*[​](#blockinflightops_name "Direct link to blockinflightops_name")

This value counts the number of I/O requests that have been issued to the device driver but have not yet completed. It does not include IO requests that are in the queue but not yet issued to the device driver. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockQueueTime\_*name*[​](#blockqueuetime_name "Direct link to blockqueuetime_name")

This value counts the number of milliseconds that IO requests have waited on this block device. If there are multiple IO requests waiting, this value will increase as the product of the number of milliseconds times the number of requests waiting. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockReadBytes\_*name*[​](#blockreadbytes_name "Direct link to blockreadbytes_name")

Number of bytes read from the block device. It can be lower than the number of bytes read from the filesystem due to the usage of the OS page cache, that saves IO. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockReadMerges\_*name*[​](#blockreadmerges_name "Direct link to blockreadmerges_name")

Number of read operations requested from the block device and merged together by the OS IO scheduler. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockReadOps\_*name*[​](#blockreadops_name "Direct link to blockreadops_name")

Number of read operations requested from the block device. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockReadTime\_*name*[​](#blockreadtime_name "Direct link to blockreadtime_name")

Time in seconds spend in read operations requested from the block device, summed across all the operations. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockWriteBytes\_*name*[​](#blockwritebytes_name "Direct link to blockwritebytes_name")

Number of bytes written to the block device. It can be lower than the number of bytes written to the filesystem due to the usage of the OS page cache, that saves IO. A write to the block device may happen later than the corresponding write to the filesystem due to write-through caching. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockWriteMerges\_*name*[​](#blockwritemerges_name "Direct link to blockwritemerges_name")

Number of write operations requested from the block device and merged together by the OS IO scheduler. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockWriteOps\_*name*[​](#blockwriteops_name "Direct link to blockwriteops_name")

Number of write operations requested from the block device. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### BlockWriteTime\_*name*[​](#blockwritetime_name "Direct link to blockwritetime_name")

Time in seconds spend in write operations requested from the block device, summed across all the operations. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. Source: `/sys/block`. See <https://www.kernel.org/doc/Documentation/block/stat.txt>

### CPUFrequencyMHz\_*name*[​](#cpufrequencymhz_name "Direct link to cpufrequencymhz_name")

The current frequency of the CPU, in MHz. Most of the modern CPUs adjust the frequency dynamically for power saving and Turbo Boosting.

### DictionaryMaxUpdateDelay[​](#dictionarymaxlastsuccessfulupdatetime "Direct link to DictionaryMaxUpdateDelay")

The maximum delay (in seconds) of dictionary update.

### DictionaryTotalFailedUpdates[​](#dictionaryloadfailed "Direct link to DictionaryTotalFailedUpdates")

Number of errors since last successful loading in all dictionaries.

### DiskAvailable\_*name*[​](#diskavailable_name "Direct link to diskavailable_name")

Available bytes on the disk (virtual filesystem). Remote filesystems can show a large value like 16 EiB.

### DiskTotal\_*name*[​](#disktotal_name "Direct link to disktotal_name")

The total size in bytes of the disk (virtual filesystem). Remote filesystems can show a large value like 16 EiB.

### DiskUnreserved\_*name*[​](#diskunreserved_name "Direct link to diskunreserved_name")

Available bytes on the disk (virtual filesystem) without the reservations for merges, fetches, and moves. Remote filesystems can show a large value like 16 EiB.

### DiskUsed\_*name*[​](#diskused_name "Direct link to diskused_name")

Used bytes on the disk (virtual filesystem). Remote filesystems not always provide this information.

### FilesystemCacheBytes[​](#filesystemcachebytes "Direct link to FilesystemCacheBytes")

Total bytes in the `cache` virtual filesystem. This cache is hold on disk.

### FilesystemCacheFiles[​](#filesystemcachefiles "Direct link to FilesystemCacheFiles")

Total number of cached file segments in the `cache` virtual filesystem. This cache is hold on disk.

### FilesystemLogsPathAvailableBytes[​](#filesystemlogspathavailablebytes "Direct link to FilesystemLogsPathAvailableBytes")

Available bytes on the volume where ClickHouse logs path is mounted. If this value approaches zero, you should tune the log rotation in the configuration file.

### FilesystemLogsPathAvailableINodes[​](#filesystemlogspathavailableinodes "Direct link to FilesystemLogsPathAvailableINodes")

The number of available inodes on the volume where ClickHouse logs path is mounted.

### FilesystemLogsPathTotalBytes[​](#filesystemlogspathtotalbytes "Direct link to FilesystemLogsPathTotalBytes")

The size of the volume where ClickHouse logs path is mounted, in bytes. It's recommended to have at least 10 GB for logs.

### FilesystemLogsPathTotalINodes[​](#filesystemlogspathtotalinodes "Direct link to FilesystemLogsPathTotalINodes")

The total number of inodes on the volume where ClickHouse logs path is mounted.

### FilesystemLogsPathUsedBytes[​](#filesystemlogspathusedbytes "Direct link to FilesystemLogsPathUsedBytes")

Used bytes on the volume where ClickHouse logs path is mounted.

### FilesystemLogsPathUsedINodes[​](#filesystemlogspathusedinodes "Direct link to FilesystemLogsPathUsedINodes")

The number of used inodes on the volume where ClickHouse logs path is mounted.

### FilesystemMainPathAvailableBytes[​](#filesystemmainpathavailablebytes "Direct link to FilesystemMainPathAvailableBytes")

Available bytes on the volume where the main ClickHouse path is mounted.