I do not really think HDD is that old. I've got it brand new less than year ago. Here is smartctl output:It could also be that the disk is bit older and has or is starting to use its spare sectors.
nazar-pc@nazar-pc ~> sudo smartctl -a /dev/sda smartctl 6.5 2016-01-24 r4214 [x86_64-linux-4.5.0-haswell] (local build)Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org=== START OF INFORMATION SECTION === Model Family: Seagate Samsung SpinPoint M9T Device Model: ST2000LM003 HN-M201RAD Serial Number: S34RJ9CF727799 LU WWN Device Id: 5 0004cf 20dbc7ec5 Firmware Version: 2BC10004 User Capacity: 2 000 398 934 016 bytes [2,00 TB] Sector Sizes: 512 bytes logical, 4096 bytes physical Rotation Rate: 5400 rpm Form Factor: 2.5 inches Device is: In smartctl database [for details use: -P show] ATA Version is: ATA8-ACS T13/1699-D revision 6 SATA Version is: SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s) Local Time is: Wed Mar 16 01:25:17 2016 EET 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: (0x00) Offline data collection activitywas never started. Auto Offline Data Collection: Disabled.Self-test execution status: ( 0) The previous self-test routine completedwithout error or no self-test has ever been run. Total time to complete Offline data collection: (23760) 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 enteringpower-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: ( 396) minutes. SCT capabilities: (0x003f) 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 0x002f 100 100 051 Pre-fail Always - 16 2 Throughput_Performance 0x0026 252 252 000 Old_age Always - 0 3 Spin_Up_Time 0x0023 088 086 025 Pre-fail Always - 3760 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 840 5 Reallocated_Sector_Ct 0x0033 252 252 010 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 252 252 051 Old_age Always - 0 8 Seek_Time_Performance 0x0024 252 252 015 Old_age Offline - 0 9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 6208 10 Spin_Retry_Count 0x0032 252 252 051 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 678 191 G-Sense_Error_Rate 0x0022 100 100 000 Old_age Always - 11 192 Power-Off_Retract_Count 0x0022 252 252 000 Old_age Always - 0 194 Temperature_Celsius 0x0002 053 044 000 Old_age Always - 47 (Min/Max 17/56) 195 Hardware_ECC_Recovered 0x003a 100 100 000 Old_age Always - 0 196 Reallocated_Event_Count 0x0032 252 252 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 252 252 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0030 252 252 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0036 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x002a 100 100 000 Old_age Always - 20 223 Load_Retry_Count 0x0032 100 100 000 Old_age Always - 7 225 Load_Cycle_Count 0x0032 100 100 000 Old_age Always - 7035SMART 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 0Note: revision number not 1 implies that no selective self-test has ever been runSPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS 1 0 0 Completed [00% left] (0-65535) 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.
gnome-disks says it worked 15 days and 8 minutes
Well, it is not that bad and hard in reality. Every 15 minutes I'm transfering 3 diffs. Right now HDD contains 453 subvolumes totally, 34% of 359 GiB partition space used. After writing last message I've decided to collect diffs for further analysis.I also almost never look at the backups, and when I do, indeed scanning through a 1000 snapshots fs on spinning disk takes time. If a script does that every 15mins, and the fs uses LZO compression and there is another active partition then you will have to deal with the slowness.
So /home subvolume's diffs ranging from 6 to 270 MiB. Typically 30-40 MiB./root subvolume's diffs ranging from 10 KiB to 380 MiB (during software updates). Typically 40-80 KiB.
/web (source code here) subvolume's diffs ranging from bytes to 1 MiB, typically 150 KiB.
So generally when I'm watching movie or playing some game (not changing source code, not updating software and not doing anything that might cause significant changes in /home subvolume) I'll get about 30 MiB of diff in total. This is not that much for SATA3 HDD, it shouldn't stuck for some seconds when everything is so slow that video stops completely for few seconds.
Maybe BTRFS construction requires this small diff to make a big party all over HDD, I don't know, but there is some problem here for sure.
I'm not sure what you mean exactly by searching. My first SSD died during waking up from suspend mode, it worked perfectly till last moment. It was not used for critical data at that time, but now I understand clearly that SSD failure can happen at any time. Having RAID0 of 2 SSDs it 2 times more risky, so I'm not ready to lose anything beyond 15 minutes threshold. I'd rather end up having another HDD purely for backup purposes.You could adapt the script or backup method not to search every time, but to just write the next diff send|receive and only step back and search if this fails. Or keeping more 15min snapshots only on SSD and lower the rate of send|receive them to HDD
Interesting question: is there any tool to see the whole picture about how btrfs partition is fragmented? I saw many tools for NTFS on Windows that show nice picture, but not for Linux filesystems. Saw answer on StackOverlow about fsck, but btrfsck doesn't provide similar output.
Also, I can't really run defragmentation anyway since all backups are read-only.
Sincerely, Nazar Mokrynskyi github.com/nazar-pc Skype: nazar-pc Diaspora: naza...@diaspora.mokrynskyi.com Tox: A9D95C9AA5F7A3ED75D83D0292E22ACE84BA40E912185939414475AF28FD2B2A5C8EF5261249 On 16.03.16 01:11, Henk Slager wrote:
On Tue, Mar 15, 2016 at 1:47 AM, Nazar Mokrynskyi <na...@mokrynskyi.com> wrote:Some update since last time (few weeks ago). All filesystems are mounted with noatime, I've also added mounting optimization - so there is no problem with remounting filesystem every time, it is done only once. Remounting optimization helped by reducing 1 complete snapshot + send/receive cycle by some seconds, but otherwise it is still very slow when `btrfs receive` is active.OK, great that the umount+mount is gone. I think most time is unfortunately spent in seeks; I think over time and due to various factors, both free space and files are highly fragmented on your disk. It could also be that the disk is bit older and has or is starting to use its spare sectors.I'm not considering bcache + btrfs as potential setup because I do not currently have free SSD for it and basically spending SSD besides HDD for backup partition feels like a bit of overkill (especially for desktop use).Yes I think so too; For backup, I am also a bit reluctant to use bcache. But the big difference is that you do a snapshot transfer every 15minute while I do that only every 24hour. So I almost dont care how long the send|receive takes in the middle of the night. I also almost never look at the backups, and when I do, indeed scanning through a 1000 snapshots fs on spinning disk takes time. If a script does that every 15mins, and the fs uses LZO compression and there is another active partition then you will have to deal with the slowness. And if the files are mostly small, like source-trees, it gets even worse. So it is about 100x more creates+deletes of subvolumes. To be honest, it is just requiring too much from a HDD I think, knowing that btrfs is CoW. On a fresh fs it might work OK in the beginning, but over time... You could adapt the script or backup method not to search every time, but to just write the next diff send|receive and only step back and search if this fails. Or keeping more 15min snapshots only on SSD and lower the rate of send|receive them to HDD Another thing you could do is skip the receive step; So just pipe the 15min snapshot diff to a stream file and just leave it on the backup HDD until you need files from the backup. Only then do a series of incremental receives of the streams. An every now and then a full (non-incremental) send.My current kernel is 4.5.0 stable, btrfs-tools still 4.4-1 from Ubuntu 16.04 repository as of today. As I'm reading mailing list there are other folks having similar performance issues. So can we debug things to find the root cause and fix it at some point?Indeed there are multiple reports with similar symptoms. I think it is not really that one should see it as an error or root cause or some fault. It is further optimization and then specifically for harddisks. Or implementing additional concepts just for harddisks. For (parity) RAID (by btrfs itself, not DM or MD etc), one can exploit parallelism, but it is not trivial to get that fully optimized for all device configurations and tasks.My C/C++/Kernel/BTRFS knowledges are scarce, which is why some assistance here is needed from someone more experienced.It is all about HDD seek times in the first place. There are many thoughts, articles and benchmarks about this over the years on the internet, but I just found this one from last year about XFS: https://lkml.org/lkml/2015/4/29/776 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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