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I just bought a new 8tb hard drive and do not seem to be able to get all the space available.
TiB to TB calculation means there should be about 7.3TB in total which is shown correctly:
# df -h /dev/sdc1
Filesystem Size Used Avail Use% Mounted on
/dev/sdc1 7.3T 51M 6.9T 1% /run/media/server/backup
There are two strange things going on here:
1. There's nothing on the drive so I'm not sure where that 51MB is coming from, perhaps it's required by the filesystem, I have no idea, it if it was just that I wouldn't worry.
2. 7.3T available, 51MB used, 6.9T available. Even ignoring the 51MB used, there's 0.4T missing. Shouldn't Size = Used + Avail?
I used gparted to create a GPT partition table, then partition and format it to ext4. cgdisk shows the partition as the correct size.
It's a brand new drive so could potentially be faulty but smartctl shows everything as fine. My worry isn't so much the space, though losing nearly 500gb is rather annoying, but that the drive may be faulty.
# smartctl -a /dev/sdc
smartctl 7.0 2018-12-30 r4883 [x86_64-linux-4.20.0-arch1-1-ARCH] (local build)
Copyright (C) 2002-18, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Western Digital Red
Device Model: WDC WD80EFAX-68KNBN0
Serial Number: VAHW72VL
LU WWN Device Id: 5 000cca 099da7825
Firmware Version: 81.00A81
User Capacity: 8,001,563,222,016 bytes [8.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 5400 rpm
Form Factor: 3.5 inches
Device is: In smartctl database [for details use: -P show]
ATA Version is: ACS-2, ATA8-ACS T13/1699-D revision 4
SATA Version is: SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Tue Apr 9 14:08:59 2019 BST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
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: ( 87) 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: ( 887) 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 100 100 016 Pre-fail Always - 0
2 Throughput_Performance 0x0004 100 100 054 Old_age Offline - 0
3 Spin_Up_Time 0x0007 100 100 024 Pre-fail Always - 0
4 Start_Stop_Count 0x0012 100 100 000 Old_age Always - 1
5 Reallocated_Sector_Ct 0x0033 100 100 005 Pre-fail Always - 0
7 Seek_Error_Rate 0x000a 100 100 067 Old_age Always - 0
8 Seek_Time_Performance 0x0004 100 100 020 Old_age Offline - 0
9 Power_On_Hours 0x0012 100 100 000 Old_age Always - 0
10 Spin_Retry_Count 0x0012 100 100 060 Old_age Always - 0
12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 1
192 Power-Off_Retract_Count 0x0032 100 100 000 Old_age Always - 1
193 Load_Cycle_Count 0x0012 100 100 000 Old_age Always - 1
194 Temperature_Celsius 0x0002 147 147 000 Old_age Always - 44 (Min/Max 14/44)
196 Reallocated_Event_Count 0x0032 100 100 000 Old_age Always - 0
197 Current_Pending_Sector 0x0022 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0008 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x000a 200 200 000 Old_age Always - 0
SMART Error Log Version: 1
No Errors Logged
SMART Self-test log structure revision number 1
No self-tests have been logged. [To run self-tests, use: smartctl -t]
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.
Last edited by Tom B (2019-04-09 13:39:28)
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There's 5% reserved space on ext4 by default. You can disable that manually and set it to 0%. I don't remember the command for this.
Here's a calculation using those 5% where I end up with 6.9 TiB:
$ bc -l <<< '8001563222016 * 0.95 / 2^40'
6.91351038850843906402
That 8001563222016 number I got out of your smartctl output.
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There's 5% reserved space on ext4 by default. You can disable that manually and set it to 0%. I don't remember the command for this.
Here's a calculation using those 5% where I end up with 6.9 TiB:
$ bc -l <<< '8001563222016 * 0.95 / 2^40' 6.91351038850843906402
That 8001563222016 number I got out of your smartctl output.
Aha, thank you. Looking at the man page for mkfs, it's -m [percentage]. It looks like this is useful to avoid fragmentation, though approaching 500gb is excessive.
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It's nothing to do with fragmentation, it's reserved for root use only so that a runaway user process can't fill up the filesystem and bring down the system. 5% used to be a sensible amount back when drives were measured in MB/GB but nowadays it's a ridiculous default. On a filesystem that's going to be used for data storage only I routinely set it to 0%.
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The man page suggests it does help with fragmentation, though I'd assume it only really makes a difference if the disk is nearly full.
-m reserved-blocks-percentage
Specify the percentage of the filesystem blocks reserved for the super-user. This avoids fragmentation, and allows root-owned daemons, such as syslogd(8), to continue to function correctly after non-privileged processes are prevented from writing to the filesystem. The default percentage is 5%.
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