Re: BTRFS balance fails with -dusage=100

[Moby <moby@mobsternet.com>]

On 06/24/2015 12:33 PM, Moby wrote:
>
>
> On 06/22/2015 10:53 PM, Moby wrote:
>> OpenSuSE 13.2 system with single BTRFS / mounted on top of /dev/md1. 
>> /dev/md1 is md raid5 across 4 SATA disks.
>>
>> System details are:
>>
>> Linux suse132 4.0.5-4.g56152db-default #1 SMP Thu Jun 18 15:11:06 UTC 
>> 2015 (56152db) x86_64 x86_64 x86_64 GNU/Linux
>>
>> btrfs-progs v4.1+20150622
>>
>> Label: none  uuid: 33b98d97-606b-4968-a266-24a48a9fe50d
>>     Total devices 1 FS bytes used 884.21GiB
>>     devid    1 size 1.36TiB used 889.06GiB path /dev/md1
>>
>>
>> Data, single: total=885.00GiB, used=883.12GiB
>> System, DUP: total=32.00MiB, used=144.00KiB
>> Metadata, DUP: total=2.00GiB, used=1.09GiB
>> GlobalReserve, single: total=384.00MiB, used=0.00B
>>
>>
>> Relevant entries from log are:
>> 2015-06-22T22:46:32.238011-05:00 suse132 kernel: [90193.446128] 
>> BTRFS: bdev /dev/md1 errs: wr 9977, rd 0, flush 0, corrupt 0, gen 0
>> 2015-06-22T22:46:32.238050-05:00 suse132 kernel: [90193.446158] 
>> BTRFS: bdev /dev/md1 errs: wr 9978, rd 0, flush 0, corrupt 0, gen 0
>> 2015-06-22T22:46:32.238054-05:00 suse132 kernel: [90193.446179] 
>> BTRFS: bdev /dev/md1 errs: wr 9979, rd 0, flush 0, corrupt 0, gen 0
>>
>> System was (still is - other than btrfs balance) running fine. Then I 
>> did massive data I/O, copying and deleting and massive amounts of 
>> data to bring the system into it's present state. Once I was done 
>> with the I/O, kicked off btrfs balance start /.
>> Above command failed.  Then I started doing btrfs balance -dusage=XX /
>> This command succeeds  with XX upto and including 99.  It fails when 
>> I set XX to 100.  btrfs balance also fails if I omit the -dusage option.
>> The errors in the log make no sense to me since the md raid device is 
>> not reporting any errors at all.  Also running btrfs scrub reports no 
>> errors at all.
>>
>> Any ideas on how to get btrfs balance to succeed without errors would 
>> be welcome.
>>
>> Regards,
>>
>> --Moby
>> -- 
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>> linux-btrfs" in
>>
>>
>
> On another run with -duage=95, I am now seeing the following (negative 
> percentage left value!)
>
> Every 15.0s: sh -c date;btrfs balance status -v /       Wed Jun 24 
> 12:29:12 2015
>
> Wed Jun 24 12:29:12 CDT 2015
> Balance on '/' is running
> 306 out of about 145 chunks balanced (312 considered), -111% left
> Dumping filters: flags 0x1, state 0x1, force is off
>   DATA (flags 0x2): balancing, usage=95
>
> --Moby
> -- 
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>
Upgrading to kernel 4.1.0-1.gfcf8349-default and btrfs-progs 
v4.1+20150622 seems to have fixed the problem.  btrfs balance now 
completes without any errors.

-- 
--Moby

They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.  -- Benjamin Franklin