While I was installing Ubuntu 13.10, it asked me to make a swap partition. I made it ~5.6GB, as I didn't know what it was or anything.
Ubuntu – A swap partition and why is it important
partitioningswap
Related Solutions
Just a shoot in the dark, but IMHO your swap partition isn't damaged at all. I've already seen discrepancies between fdisk and gparted and, it's sad to say, but fdisk is almost always right.
Try a:
#> cat /proc/meminfo | grep -i swap
SwapCached: 10632 kB
SwapTotal: 2094076 kB
SwapFree: 2053324 kB
you should see that your swap space is actually in use (or at least I hope so).
The explaination for that "unreadable" /dev/mapper/cryptswap1 partition is that cryptswap1 is actually a mapped encrypted swapspace, so it should be fine that no one can understand what's in there. If you want to disable it, you can look at this thread: How to disable cryptswap?
Last but not least, your SMART status: at first sight (just watching the read error rate and the seek error rate), I'd have said that your drive was about to melt down. But, no, it's fine, I have a drive whose SMART says exactly the same. I'll post the full output just for reference (both for me and others) for future visits.
#> sudo smartctl --all /dev/sda
smartctl 5.41 2011-06-09 r3365 [x86_64-linux-3.2.0-24-generic] (local build)
Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net
=== START OF INFORMATION SECTION ===
Model Family: Seagate Barracuda 7200.12
Device Model: ST3250318AS
Serial Number: 9VM2R3AN
LU WWN Device Id: 5 000c50 015aa8d47
Firmware Version: CC35
User Capacity: 250,059,350,016 bytes [250 GB]
Sector Size: 512 bytes logical/physical
Device is: In smartctl database [for details use: -P show]
ATA Version is: 8
ATA Standard is: ATA-8-ACS revision 4
Local Time is: Sun May 27 18:03:03 2012 CEST
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: (0x82) Offline data collection activity
was completed without error.
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: ( 617) seconds.
Offline data collection
capabilities: (0x7b) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
command.
Offline surface scan supported.
Self-test supported.
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: ( 1) minutes.
Extended self-test routine
recommended polling time: ( 52) minutes.
Conveyance self-test routine
recommended polling time: ( 2) minutes.
SCT capabilities: (0x103f) SCT Status supported.
SCT Error Recovery Control supported.
SCT Feature Control supported.
SCT Data Table supported.
SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x000f 118 099 006 Pre-fail Always - 196559365
3 Spin_Up_Time 0x0003 097 097 000 Pre-fail Always - 0
4 Start_Stop_Count 0x0032 100 100 020 Old_age Always - 320
5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 0
7 Seek_Error_Rate 0x000f 067 060 030 Pre-fail Always - 6277671
9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 517
10 Spin_Retry_Count 0x0013 100 100 097 Pre-fail Always - 0
12 Power_Cycle_Count 0x0032 100 100 020 Old_age Always - 158
183 Runtime_Bad_Block 0x0032 100 100 000 Old_age Always - 0
184 End-to-End_Error 0x0032 100 100 099 Old_age Always - 0
187 Reported_Uncorrect 0x0032 100 100 000 Old_age Always - 0
188 Command_Timeout 0x0032 100 099 000 Old_age Always - 41
189 High_Fly_Writes 0x003a 100 100 000 Old_age Always - 0
190 Airflow_Temperature_Cel 0x0022 065 065 045 Old_age Always - 35 (Min/Max 21/35)
194 Temperature_Celsius 0x0022 035 040 000 Old_age Always - 35 (0 12 0 0)
195 Hardware_ECC_Recovered 0x001a 052 045 000 Old_age Always - 196559365
197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0010 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x003e 200 200 000 Old_age Always - 0
240 Head_Flying_Hours 0x0000 100 253 000 Old_age Offline - 72748156060552
241 Total_LBAs_Written 0x0000 100 253 000 Old_age Offline - 968998393
242 Total_LBAs_Read 0x0000 100 253 000 Old_age Offline - 939693204
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.
And I have another drive that looks more "normal":
#> sudo smartctl --all /dev/sdc
smartctl 5.42 2011-10-20 r3458 [x86_64-linux-3.0.6-gentoo-goomba-test-3]
(local build)
Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net
=== START OF INFORMATION SECTION ===
Model Family: Western Digital Caviar Green (Adv. Format)
Device Model: WDC WD20EARS-00MVWB0
Serial Number: WD-WCAZA2437330
LU WWN Device Id: 5 0014ee 205473c89
Firmware Version: 51.0AB51
User Capacity: 2,000,398,934,016 bytes [2,00 TB]
Sector Size: 512 bytes logical/physical
Device is: In smartctl database [for details use: -P show]
ATA Version is: 8
ATA Standard is: Exact ATA specification draft version not indicated
Local Time is: Sun May 27 18:16:09 2012 CEST
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: (0x84) Offline data collection activity
was suspended by an interrupting
command from host.
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: (37500) seconds.
Offline data collection
capabilities: (0x7b) SMART execute Offline immediate.
Auto Offline data collection on/off
support.
Suspend Offline collection upon new
command.
Offline surface scan supported.
Self-test supported.
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: ( 255) minutes.
Conveyance self-test routine
recommended polling time: ( 5) minutes.
SCT capabilities: (0x3035) SCT Status 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 0x002f 200 200 051 Pre-fail Always - 0
3 Spin_Up_Time 0x0027 253 253 021 Pre-fail Always - 1233
4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 390
5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0
7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0
9 Power_On_Hours 0x0032 094 094 000 Old_age Always - 4988
10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0
11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0
12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 388
192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 33
193 Load_Cycle_Count 0x0032 135 135 000 Old_age Always - 197801
194 Temperature_Celsius 0x0022 119 109 000 Old_age Always - 31
196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 199 000 Old_age Always - 451
200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 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.
And another one with some "real" error, that however is still alive after several months of tiny complaints:
#> sudo smartctl --all /dev/sda
smartctl 5.42 2011-10-20 r3458 [x86_64-linux-3.0.6-gentoo-goomba-test-3] (local build)
Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net
=== START OF INFORMATION SECTION ===
Model Family: Seagate Maxtor DiamondMax 20
Device Model: MAXTOR STM3160211AS
Serial Number: 6PT56QN7
Firmware Version: 3.AAE
User Capacity: 160,041,885,696 bytes [160 GB]
Sector Size: 512 bytes logical/physical
Device is: In smartctl database [for details use: -P show]
ATA Version is: 7
ATA Standard is: Exact ATA specification draft version not indicated
Local Time is: Sun May 27 18:33:59 2012 CEST
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: (0x82) Offline data collection activity
was completed without error.
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: ( 430) 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: ( 1) minutes.
Extended self-test routine
recommended polling time: ( 54) minutes.
SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x000f 102 087 006 Pre-fail Always - 4542948
3 Spin_Up_Time 0x0003 095 095 000 Pre-fail Always - 0
4 Start_Stop_Count 0x0032 100 100 020 Old_age Always - 1011
5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 11
7 Seek_Error_Rate 0x000f 089 060 030 Pre-fail Always - 846828717
9 Power_On_Hours 0x0032 086 086 000 Old_age Always - 13126
10 Spin_Retry_Count 0x0013 100 100 097 Pre-fail Always - 0
12 Power_Cycle_Count 0x0032 100 100 020 Old_age Always - 1019
187 Reported_Uncorrect 0x0032 100 100 000 Old_age Always - 0
189 High_Fly_Writes 0x003a 100 100 000 Old_age Always - 0
190 Airflow_Temperature_Cel 0x0022 064 052 045 Old_age Always - 36 (Min/Max 22/37)
194 Temperature_Celsius 0x0022 036 048 000 Old_age Always - 36 (0 14 0 0 0)
195 Hardware_ECC_Recovered 0x001a 050 046 000 Old_age Always - 11583613
197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0010 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x003e 200 169 000 Old_age Always - 48
200 Multi_Zone_Error_Rate 0x0000 100 253 000 Old_age Offline - 0
202 Data_Address_Mark_Errs 0x0032 100 253 000 Old_age Always - 0
SMART Error Log Version: 1
ATA Error Count: 204 (device log contains only the most recent five errors)
CR = Command Register [HEX]
FR = Features Register [HEX]
SC = Sector Count Register [HEX]
SN = Sector Number Register [HEX]
CL = Cylinder Low Register [HEX]
CH = Cylinder High Register [HEX]
DH = Device/Head Register [HEX]
DC = Device Command Register [HEX]
ER = Error register [HEX]
ST = Status register [HEX]
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.
Error 204 occurred at disk power-on lifetime: 5852 hours (243 days + 20 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
84 51 2d 72 00 00 e0 Error: ICRC, ABRT 45 sectors at LBA = 0x00000072 = 114
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 3e 61 00 00 e0 00 00:01:52.203 READ DMA
27 00 00 00 00 00 e0 00 00:01:52.133 READ NATIVE MAX ADDRESS EXT
ec 00 00 00 00 00 a0 00 00:01:52.125 IDENTIFY DEVICE
ef 03 42 00 00 00 a0 00 00:01:52.104 SET FEATURES [Set transfer mode]
27 00 00 00 00 00 e0 00 00:01:46.941 READ NATIVE MAX ADDRESS EXT
Error 203 occurred at disk power-on lifetime: 5852 hours (243 days + 20 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
84 51 2d 72 00 00 e0 Error: ICRC, ABRT 45 sectors at LBA = 0x00000072 = 114
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 3e 61 00 00 e0 00 00:01:45.519 READ DMA
c8 00 02 5f 00 00 e0 00 00:01:45.511 READ DMA
27 00 00 00 00 00 e0 00 00:01:45.503 READ NATIVE MAX ADDRESS EXT
ec 00 00 00 00 00 a0 00 00:01:45.431 IDENTIFY DEVICE
ef 03 42 00 00 00 a0 00 00:01:45.423 SET FEATURES [Set transfer mode]
Error 202 occurred at disk power-on lifetime: 5852 hours (243 days + 20 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
84 51 00 60 00 00 e0 Error: ICRC, ABRT at LBA = 0x00000060 = 96
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 02 5f 00 00 e0 00 00:01:45.519 READ DMA
27 00 00 00 00 00 e0 00 00:01:45.511 READ NATIVE MAX ADDRESS EXT
ec 00 00 00 00 00 a0 00 00:01:45.503 IDENTIFY DEVICE
ef 03 42 00 00 00 a0 00 00:01:45.431 SET FEATURES [Set transfer mode]
27 00 00 00 00 00 e0 00 00:01:45.423 READ NATIVE MAX ADDRESS EXT
Error 201 occurred at disk power-on lifetime: 5852 hours (243 days + 20 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
84 51 00 60 00 00 e0 Error: ICRC, ABRT at LBA = 0x00000060 = 96
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 02 5f 00 00 e0 00 00:01:44.035 READ DMA
25 00 08 af 8a a1 e0 00 00:01:43.980 READ DMA EXT
27 00 00 00 00 00 e0 00 00:01:43.972 READ NATIVE MAX ADDRESS EXT
ec 00 00 00 00 00 a0 00 00:01:43.968 IDENTIFY DEVICE
ef 03 42 00 00 00 a0 00 00:01:43.904 SET FEATURES [Set transfer mode]
Error 200 occurred at disk power-on lifetime: 5852 hours (243 days + 20 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
84 51 00 b6 8a a1 e0 Error: ICRC, ABRT at LBA = 0x00a18ab6 = 10586806
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
25 00 08 af 8a a1 e0 00 00:01:44.035 READ DMA EXT
25 00 06 41 8a a1 e0 00 00:01:43.980 READ DMA EXT
27 00 00 00 00 00 e0 00 00:01:43.972 READ NATIVE MAX ADDRESS EXT
ec 00 00 00 00 00 a0 00 00:01:43.968 IDENTIFY DEVICE
ef 03 42 00 00 00 a0 00 00:01:43.904 SET FEATURES [Set transfer mode]
SMART Self-test log structure revision number 1
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.
For what concerns the read speed benchmark, I think that a speed decrease over time is normal. I suspect that caching mechanisms make the disk appear faster in the initial phase of testing, and slower at the end. However I see that your "worst" read speed is around 80MB/s that is well above my "best average" read speed (around 60MB/s), so I wouldn't worry about this aspect.
Summary
The Swap Area is just fake RAM that lives on your hard drive. It is much slower than actual RAM, but is necessary in many cases to keep a computer running normally. A good rule of thumb is to have as much swap space as you do normal RAM.
Memory
Your computer has a couple different kinds of memory that we need to talk about. Your files and operating system are stored on your hard drive (commonly HDD). This is relatively slow and cheap, but is persistent between system shutdowns. Your computer also has RAM (Random Access Memory) which is much faster, more expensive, and loses its contents when your computer loses power. In order to run a program, it is first copied from your HDD to your RAM (which is much faster) so that it can execute in close to real time.
Swap
However, we should ask the question: what happens if you run out of RAM but want to open another program? The answer isn't good; your computer freezes until there is enough RAM to complete the operation (this is commonly called "thrashing"). Although you might only have a few Gigabytes of RAM, most computers have more HDD space than they know what to do with. So we can use some of that extra space as fake "RAM" in a pinch. That is what swap space is; emergency RAM that lives on your hard drive.
Now that we have some swap space on our hard drive, running out of RAM isn't as big of a deal. Now when we run out and wish to open another program, the operating system looks through all of the open programs currently in RAM, and chooses one that hasn't been used for a while. It then copies that program out of RAM and stores it in swap space, freeing up room for the new program. If in the future we want to access the "swapped out" program, the operating system simply copies it back to RAM, potentially swapping out other programs in the process.
Partition vs. File
When creating a swap space, you have two choices. You can make a separate partition on your hard drive, which is recommended in Ubuntu and necessary if you wish to hibernate your system. Or, you can create a Swap File (called the Pagefile in Windows) on your hard drive. Technically a swap partition will out-perform a swap file, but the difference will likely be negligible. Also note that if you have multiple linux distributions on the same hard drive, they can share a single swap partition (swap partitions do not have a file system).
Guidelines
If you are installing Ubuntu for the first time, you might as well make a swap partition. This is the default in the Ubuntu installer, and also my personal recommendation. On the other hand, if you do not have any swap space and would like to add some after installation, it may be much easier and faster to use a swap file.
In terms of size, if you have no idea how big to make it, a good baseline (and the default in the Ubuntu installer) is to have the same amount of swap as you do RAM. That being said, this is only a very general guideline, and depends on how you use your system. There is nothing wrong with having no swap space. If you start running out of RAM, just make your swap space larger.
See also
- Ubuntu help - Official swap FAQ
- AskUbuntu - how much swap you need
- ServerFault - performance of partition vs. file
- The comments for technical details on partition vs. file
Best Answer
Simply said it is an additional space provided for the operating system to increase it's operating memory. It allows for running more software at once or to operate with larger data.
Something alike also exists in windows, only they implement it as file on a new file system, which is likely done for efficiency.