Preparing the storage
Install hdparm and smartmontools
Install hdparm and the SMART monitoring tools.
# apt install hdparm smartmontools
Identify the right hard drive
Make sure you identify the correct drive, as some of the commands will destroy data. If you don’t understand the commands, then check them first. You have been warned.
Identify the block size
Knowing the block size of the device is important. It will help optimising writes, and in the case of SSD or flash drives avoid write amplification and wear and tear.
[List details of all drives]
# fdisk -l
[...]
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 512 bytes / 4096 bytes
[..]
[List details of a specific drive]
# fdisk -l /dev/sda
[...]
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
[...]
# smartctl --all /dev/sda
[...]
Sector Sizes: 512 bytes logical, 4096 bytes physical
[...]
Pay attention to the physical/optimal size. This is the one that matters.
SSDs will hide the true size of the pages and blocks. Even the same drive models might be built with different components, so getting it right is tricky.
Some suggest that 4kB is a generally good size for SSDs: https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/ssd-server-storage-applications-paper.pdf
Use the drive’s sector physical size to match the ZFS ashift (block size).
Retrieve drive IDs
When setting ZFS pools or using disk tools it is best to avoid using device names as they can easily change their order. Using the drive ID or serial will ensure that no matter in which port or in which order the drives are plugged it will be the correct drive selected.
This matters with any disk accessing utility if you have several drives, or will be inserting external drives regularly.
$ ls -l /dev/disk/by-id/
[...]
lrwxrwxrwx 1 root root 9 Mar 9 13:16 usb-TOSHIBA_External_USB_3.0_20150612015531-0:0 -> ../../sda
[...]
You can also extract model and serial numbers with hdparm.
# hdparm -i /dev/sda
/dev/sda:
Model=WDC WD10EZEX-08WN4A0, FwRev=01.01A01, SerialNo=WD-WCC6Y5FXAPHV
[...]
Even better, depending on the use of the drive, and if there is a plan to add mirror drives, is to partition the drive to ensure there is enough space if a different drive model is later added. Although I believe ZFS already does this and rounds down partitions using Mebibytes.
Test for damaged sectors
An additional and optional step is to test the hard drive for damaged sectors. This kind of test tends to be destructive so it is best if it is done before configuring the pools.
badblocks is a useful tool to achieve this.
It is installed by default, but if not you can do it manually.
# apt install e2fsprogs
A destructive test can be done with:
# badblocks -wsv -b 4096 /dev/sda
If you want to run the test while preserving the disk data you can run it in a non-destructive way. This will take longer.
# badblocks -nsv -b 4096 /dev/sda
ZFS has built-in checks and protection so in most cases you can skip this step.
Setting hard drive sleep patterns
Above I explained that using disk IDs is always a better idea. For simplicity, I will be using device names in several examples below, but I still advise using IDs or serials.
Check if the disk supports sleep
Check if the drive supports standby.
# hdparm -y /dev/sda
If supported the output will be:
/dev/sda:
issuing standby command
Any other output might indicate that the drive doesn’t support sleep, or that a different tool/setting might be required.
Next, check if the drive supports write cache:
# hdparm -I /dev/sda | grep -i 'Write cache'
The expected output is:
* Write cache
The * indicates that the feature is supported.
An example of a complete hdparm output from a drive is shown below for reference. Different drives, with different features, will show different output, or even none at all.
# hdparm -I /dev/sda
/dev/sda:
ATA device, with non-removable media
Model Number: TOSHIBA MD04ACA500
Serial Number: 55OBK0SPFPHC
Firmware Revision: FP2A
Transport: Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0
Standards:
Supported: 8 7 6 5
Likely used: 8
Configuration:
Logical max current
cylinders 16383 16383
heads 16 16
sectors/track 63 63
--
CHS current addressable sectors: 16514064
LBA user addressable sectors: 268435455
LBA48 user addressable sectors: 9767541168
Logical Sector size: 512 bytes
Physical Sector size: 4096 bytes
Logical Sector-0 offset: 0 bytes
device size with M = 1024*1024: 4769307 MBytes
device size with M = 1000*1000: 5000981 MBytes (5000 GB)
cache/buffer size = unknown
Form Factor: 3.5 inch
Nominal Media Rotation Rate: 7200
Capabilities:
LBA, IORDY(can be disabled)
Queue depth: 32
Standby timer values: spec'd by Standard, no device specific minimum
R/W multiple sector transfer: Max = 16 Current = 16
Advanced power management level: 128
DMA: sdma0 sdma1 sdma2 mdma0 mdma1 *mdma2 udma0 udma1 udma2 udma3 udma4 udma5
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=120ns IORDY flow control=120ns
Commands/features:
Enabled Supported:
* SMART feature set
Security Mode feature set
* Power Management feature set
* Write cache
* Look-ahead
* Host Protected Area feature set
* WRITE_BUFFER command
* READ_BUFFER command
* NOP cmd
* DOWNLOAD_MICROCODE
* Advanced Power Management feature set
SET_MAX security extension
* 48-bit Address feature set
* Device Configuration Overlay feature set
* Mandatory FLUSH_CACHE
* FLUSH_CACHE_EXT
* SMART error logging
* SMART self-test
* General Purpose Logging feature set
* WRITE_{DMA|MULTIPLE}_FUA_EXT
* 64-bit World wide name
* WRITE_UNCORRECTABLE_EXT command
* {READ,WRITE}_DMA_EXT_GPL commands
* Segmented DOWNLOAD_MICROCODE
unknown 119[7]
* Gen1 signaling speed (1.5Gb/s)
* Gen2 signaling speed (3.0Gb/s)
* Gen3 signaling speed (6.0Gb/s)
* Native Command Queueing (NCQ)
* Host-initiated interface power management
* Phy event counters
* Host automatic Partial to Slumber transitions
* Device automatic Partial to Slumber transitions
* READ_LOG_DMA_EXT equivalent to READ_LOG_EXT
DMA Setup Auto-Activate optimization
Device-initiated interface power management
* Software settings preservation
* SMART Command Transport (SCT) feature set
* SCT Write Same (AC2)
* SCT Error Recovery Control (AC3)
* SCT Features Control (AC4)
* SCT Data Tables (AC5)
* reserved 69[3]
Security:
Master password revision code = 65534
supported
not enabled
not locked
not frozen
not expired: security count
supported: enhanced erase
more than 508min for SECURITY ERASE UNIT. more than 508min for ENHANCED SECURITY ERASE UNIT.
Logical Unit WWN Device Identifier: 500003964bc01970
NAA : 5
IEEE OUI : 000039
Unique ID : 64bc01970
Checksum: correct
An example of a complete smartctl output from a drive is shown below also for reference. As mentioned earlier, different systems will generate different outputs.
# smartctl --all /dev/sda
smartctl 7.1 2019-12-30 r5022 [aarch64-linux-5.4.0-1029-raspi] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Toshiba 3.5" MD04ACA... Enterprise HDD
Device Model: TOSHIBA MD04ACA500
Serial Number: 55OBK0SPFPHC
LU WWN Device Id: 5 000039 64bc01970
Firmware Version: FP2A
User Capacity: 5,000,981,078,016 bytes [5.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 7200 rpm
Form Factor: 3.5 inches
Device is: In smartctl database [for details use: -P show]
ATA Version is: ATA8-ACS (minor revision not indicated)
SATA Version is: SATA 3.0, 6.0 Gb/s (current: 3.0 Gb/s)
Local Time is: Mon Mar 8 15:02:10 2021 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
=== START OF READ SMART DATA SECTION ===
SMART Status not supported: Incomplete response, ATA output registers missing
SMART overall-health self-assessment test result: PASSED
Warning: This result is based on an Attribute check.
General SMART Values:
Offline data collection status: (0x80) Offline data collection activity
was never started.
Auto Offline Data Collection: Enabled.
Self-test execution status: ( 0) The previous self-test routine completed
without error or no self-test has ever
been run.
Total time to complete Offline
data collection: ( 120) seconds.
Offline data collection
capabilities: (0x5b) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
command.
Offline surface scan supported.
Self-test supported.
No Conveyance Self-test supported.
Selective Self-test supported.
SMART capabilities: (0x0003) Saves SMART data before entering
power-saving mode.
Supports SMART auto save timer.
Error logging capability: (0x01) Error logging supported.
General Purpose Logging supported.
Short self-test routine
recommended polling time: ( 2) minutes.
Extended self-test routine
recommended polling time: ( 533) minutes.
SCT capabilities: (0x003d) SCT Status supported.
SCT Error Recovery Control supported.
SCT Feature Control supported.
SCT Data Table supported.
SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x000b 100 100 050 Pre-fail Always - 0
2 Throughput_Performance 0x0005 100 100 050 Pre-fail Offline - 0
3 Spin_Up_Time 0x0027 100 100 001 Pre-fail Always - 9003
4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 9222
5 Reallocated_Sector_Ct 0x0033 100 100 050 Pre-fail Always - 0
7 Seek_Error_Rate 0x000b 100 100 050 Pre-fail Always - 0
8 Seek_Time_Performance 0x0005 100 100 050 Pre-fail Offline - 0
9 Power_On_Hours 0x0032 084 084 000 Old_age Always - 6418
10 Spin_Retry_Count 0x0033 253 100 030 Pre-fail Always - 0
12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 9212
191 G-Sense_Error_Rate 0x0032 100 100 000 Old_age Always - 482
192 Power-Off_Retract_Count 0x0032 100 100 000 Old_age Always - 104
193 Load_Cycle_Count 0x0032 100 100 000 Old_age Always - 9225
194 Temperature_Celsius 0x0022 100 100 000 Old_age Always - 37 (Min/Max 15/72)
196 Reallocated_Event_Count 0x0032 100 100 000 Old_age Always - 0
197 Current_Pending_Sector 0x0032 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 253 000 Old_age Always - 0
220 Disk_Shift 0x0002 100 100 000 Old_age Always - 0
222 Loaded_Hours 0x0032 085 085 000 Old_age Always - 6393
223 Load_Retry_Count 0x0032 100 100 000 Old_age Always - 0
224 Load_Friction 0x0022 100 100 000 Old_age Always - 0
226 Load-in_Time 0x0026 100 100 000 Old_age Always - 214
240 Head_Flying_Hours 0x0001 100 100 001 Pre-fail Offline - 0
SMART Error Log Version: 1
No Errors Logged
SMART Self-test log structure revision number 1
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Short offline Completed without error 00% 5617 -
# 2 Short offline Completed without error 00% 4702 -
SMART Selective self-test log data structure revision number 1
SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS
1 0 0 Not_testing
2 0 0 Not_testing
3 0 0 Not_testing
4 0 0 Not_testing
5 0 0 Not_testing
Selective self-test flags (0x0):
After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.
More information about hdparm and smartctl is available on the following sites.
hdparm
https://wiki.archlinux.org/index.php/Hdparm#Power_management_configuration
http://www.htpcguides.com/spin-down-and-manage-hard-drive-power-on-raspberry-pi/
http://www.linux-magazine.com/Online/Features/Tune-Your-Hard-Disk-with-hdparm
smartctl
https://codeyarns.com/2016/12/21/how-to-use-smartctl/
https://linuxhandbook.com/check-ssd-health/
Configure the drive standby
Check the current standby configuration.
# hdparm -B /dev/sd[a-e]
/dev/sda:
APM_level = not supported
/dev/sdb:
APM_level = 254
/dev/sdc:
APM_level = not supported
/dev/sdd:
APM_level = 254
/dev/sde:
APM_level = 254
| Values | Description |
|---|---|
| 1 to 127 | Power management is enabled. The lower the value the more aggressive the power management will be. |
| 128 to 254 | Power management is enabled but doesn’t allow spindown |
| 255 | The feature is disabled. |
| not supported | The drive doesn’t support APM. |
The status can be set manually:
# hdparm -B 127 /dev/sda
The IDE power mode status can be queried with:
# hdparm -C /dev/sd[ab]
/dev/sda:
drive state is: active/idle
/dev/sdb:
drive state is: standby
For reference, several drives can be queried at the same time using different wildcards.
# hdparm -B /dev/sd?
# hdparm -C /dev/sd*
# hdparm -I /dev/sd[a-e]
Depending on the drive manufacturer and model you might need to query the settings with different flags. Check the man page.
[Get/set the Western Digital Green Drive's "idle3" timeout value.]
# hdparm -J /dev/sd[a-e]
/dev/sda:
wdidle3 = 300 secs (or 13.8 secs for older drives)
/dev/sdb:
wdidle3 = 8.0 secs
/dev/sdc:
wdidle3 = 300 secs (or 13.8 secs for older drives)
/dev/sdd:
wdidle3 = 300 secs (or 13.8 secs for older drives)
/dev/sde:
wdidle3 = 300 secs (or 13.8 secs for older drives)
From the man page:
A setting of 30 seconds is recommended for Linux use. Permitted values are from 8 to 12 seconds, and from 30 to 300 seconds in 30-second increments. Specify a value of zero (0) to disable the WD idle3 timer completely (NOT RECOMMENDED!).
There are flags for temperature (-H for Hitachi drives), acoustic management (-M), measuring cache performance (-T), and others. Go on, read that man page. 🙂
The -S flag sets the standby/spindown timeout for the drive. Basically, how long the drive will wait with no disk activity before turning off the motor.
| Value | Description |
|---|---|
| 0 | Disable the feature. |
| 1 to 240 | Five seconds multiples (a value of 120 means 10 minutes). |
| 241 to 251 | Thirty minutes intervals (a value of 242 means 1 hour). |
Note that hdparm might wake the drive up when is queried. smartctl can query the drive without waking it.
# smartctl -i -d auto -n standby /dev/sda
Making the hdparm configuration persistent
Information about all the options is available at https://manpages.ubuntu.com/manpages/bionic/man5/hdparm.conf.5.html and also in the default configuration file generated by hdparm.
Example values from the data gathered above:
# APM setting (-B)
apm = 127
# APM setting while on battery (-B)
apm_battery = 127
# on/off drive's write caching feature (-W)
write_cache = on
# Standby (spindown) timeout for drive (-S)
spindown_time = 120
# Western Digital (WD) Green Drive's "idle3" timeout value. (-J)
wdidle3 = 300
hdparm.conf method
Edit the configuration file:
# vim /etc/hdparm.conf
And insert an entry for each drive. Select only settings/features/values that are supported by that drive, otherwise the rest of the options won’t be applied. Test, test, test!
# Drive A
/dev/disk/by-id/ata-WDC_WD40NMZM-59Y94S1_WD-WX41D296P1XX {
apm = 127
apm_battery = 127
write_cache = on
spindown_time = 120
#wdidle3 = 300
}
udev method
In my case, the above method works. I couldn’t get this one to work on my system, but it could be because of the OS. I am leaving it for reference in case it might be of help.
# vim /etc/udev/rules.d/69-disk.rules
Create an entry for each drive editing the serial number and hdparm parameters. Make sure that only supported flags are added or it will fail.
ACTION=="add", KERNEL=="sd[a-z]", ENV{ID_SERIAL_SHORT}=="S3R14LNUMB3R", RUN+="/usr/bin/hdparm -B 127 -S 120 /dev/%k"
You can also apply the same parameters to all rotational drives (all non-SSD ones) in one go.
ACTION=="add|change", KERNEL=="sd[a-z]", ATTRS{queue/rotational}=="1", RUN+="/usr/bin/hdparm -B 127 -S 120 /dev/%k"
