Dan Blazejewski wrote on 2016/02/17 18:04 -0500:
Hello,
I upgraded my kernel to 4.4.2, and btrfs-progs to 4.4. I also added
another 4TB disk and kicked off a full balance (currently 7x4TB
RAID6). I'm interested to see what an additional drive will do to
this. I'll also have to wait and see if a full system balance on a
newer version of BTRFS tools does the trick or not.
I also noticed that "btrfs device usage" shows multiple entries for
Data, RAID 6 on some drives. Is this normal? Please note that /dev/sdh
is the new disk, and I only just started the balance.
# btrfs dev usage /mnt/data
/dev/sda, ID: 5
Device size: 3.64TiB
Data,RAID6: 1.43TiB
Data,RAID6: 1.48TiB
Data,RAID6: 320.00KiB
Metadata,RAID6: 2.55GiB
Metadata,RAID6: 1.50GiB
System,RAID6: 16.00MiB
Unallocated: 733.67GiB
/dev/sdb, ID: 6
Device size: 3.64TiB
Data,RAID6: 1.48TiB
Data,RAID6: 320.00KiB
Metadata,RAID6: 1.50GiB
System,RAID6: 16.00MiB
Unallocated: 2.15TiB
/dev/sdc, ID: 7
Device size: 3.64TiB
Data,RAID6: 1.43TiB
Data,RAID6: 732.69GiB
Data,RAID6: 1.48TiB
Data,RAID6: 320.00KiB
Metadata,RAID6: 2.55GiB
Metadata,RAID6: 982.00MiB
Metadata,RAID6: 1.50GiB
System,RAID6: 16.00MiB
Unallocated: 25.21MiB
/dev/sdd, ID: 1
Device size: 3.64TiB
Data,RAID6: 1.43TiB
Data,RAID6: 732.69GiB
Data,RAID6: 1.48TiB
Data,RAID6: 320.00KiB
Metadata,RAID6: 2.55GiB
Metadata,RAID6: 982.00MiB
Metadata,RAID6: 1.50GiB
System,RAID6: 16.00MiB
Unallocated: 25.21MiB
/dev/sdf, ID: 3
Device size: 3.64TiB
Data,RAID6: 1.43TiB
Data,RAID6: 732.69GiB
Data,RAID6: 1.48TiB
Data,RAID6: 320.00KiB
Metadata,RAID6: 2.55GiB
Metadata,RAID6: 982.00MiB
Metadata,RAID6: 1.50GiB
System,RAID6: 16.00MiB
Unallocated: 25.21MiB
/dev/sdg, ID: 2
Device size: 3.64TiB
Data,RAID6: 1.43TiB
Data,RAID6: 732.69GiB
Data,RAID6: 1.48TiB
Data,RAID6: 320.00KiB
Metadata,RAID6: 2.55GiB
Metadata,RAID6: 982.00MiB
Metadata,RAID6: 1.50GiB
System,RAID6: 16.00MiB
Unallocated: 25.21MiB
/dev/sdh, ID: 8
Device size: 3.64TiB
Data,RAID6: 320.00KiB
Unallocated: 3.64TiB
Not sure how that multiple chunk type shows up.
Maybe all these shown RAID6 has different number of stripes?
Qu, in regards to your question, I ran RAID 1 on multiple disks of
different sizes. I believe I had a mix of 2x4TB, 1x2TB, and 1x3TB
drive. I replaced the 2TB drive first with a 4TB, and balanced it.
Later on, I replaced the 3TB drive with another 4TB, and balanced,
yielding an array of 4x4TB RAID1. A little while later, I wound up
sticking a fifth 4TB drive in, and converting to RAID6. The sixth 4TB
drive was added some time after that. The seventh was added just a few
minutes ago.
Personally speaking, I just came up to one method to balance all these
disks, and in fact you don't need to add a disk.
1) Balance all data chunk to single profile
2) Balance all metadata chunk to single or RAID1 profile
3) Balance all data chunk back to RAID6 profile
4) Balance all metadata chunk back to RAID6 profile
System chunk is so small that normally you don't need to bother.
The trick is, as single is the most flex chunk type, only needs one disk
with unallocated space.
And btrfs chunk allocater will allocate chunk to device with most
unallocated space.
So after 1) and 2) you should found that chunk allocation is almost
perfectly balanced across all devices, as long as they are in same size.
Now you have a balance base layout for RAID6 allocation. Should make
things go quite smooth and result a balanced RAID6 chunk layout.
Thanks,
Qu
Thanks!
On Wed, Feb 17, 2016 at 12:58 AM, Qu Wenruo <quwen...@cn.fujitsu.com> wrote:
Dan Blazejewski wrote on 2016/02/16 15:20 -0500:
Hello,
I've searched high and low about my issue, but have been unable to
turn up anything like what I'm seeing right now.
A little background: I started using BTRFS over a year ago, in RAID 1
with mixed size drives. A few months ago, I started replacing the
disks with 4 TB drives, and eventually switched over to RAID 6. I am
currently running a 6x4TB RAID6 drive configuration, which should give
me ~14.5 TB
usable, but I'm only getting around 11.
The weird thing is that It seems to completely fill 4/6 of the disks,
while leaving lots of space free on 2 of the disks. I've tried full
filesystem balances, yet the problem continues.
# btrfs fi show
Label: none uuid: 78733087-d597-4301-8efa-8e1df800b108
Total devices 6 FS bytes used 11.59TiB
devid 1 size 3.64TiB used 3.64TiB path /dev/sdd
devid 2 size 3.64TiB used 3.64TiB path /dev/sdg
devid 3 size 3.64TiB used 3.64TiB path /dev/sdf
devid 5 size 3.64TiB used 2.92TiB path /dev/sda
devid 6 size 3.64TiB used 1.48TiB path /dev/sdb
devid 7 size 3.64TiB used 3.64TiB path /dev/sdc
btrfs-progs v4.2.3
Your space really used up, as it can't found *at least 4* disk with enough
space to allocate a new chunk.
As 4 devices in your array is already filled, the rest 2 is of no means for
RAID6, and can only be allocated with Single/RAID1/RAID0.
But the real problem is, why your devices get such a unbalanced layout.
Normally, for RAID5/6, it will allocate chunks using all disk with available
space, and since all your devices are in the same size, it should result
very balanced allocation.
How did you convert to current RAID6? Did it involves balance from already
some used disks?
Thanks,
Qu
# btrfs fi df /mnt/data
Data, RAID6: total=11.67TiB, used=11.58TiB
System, RAID6: total=64.00MiB, used=1.70MiB
Metadata, RAID6: total=15.58GiB, used=13.89GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
dan@Morpheus:/mnt/data/temp$ sudo btrfs fi usage /mnt/data
# btrfs fi usage /mnt/data
WARNING: RAID56 detected, not implemented
WARNING: RAID56 detected, not implemented
WARNING: RAID56 detected, not implemented
Overall:
Device size: 21.83TiB
Device allocated: 0.00B
Device unallocated: 21.83TiB
Device missing: 0.00B
Used: 0.00B
Free (estimated): 0.00B (min: 8.00EiB)
Data ratio: 0.00
Metadata ratio: 0.00
Global reserve: 512.00MiB (used: 0.00B)
Data,RAID6: Size:11.67TiB, Used:11.58TiB
/dev/sda 2.92TiB
/dev/sdb 1.48TiB
/dev/sdc 3.63TiB
/dev/sdd 3.63TiB
/dev/sdf 3.63TiB
/dev/sdg 3.63TiB
Metadata,RAID6: Size:15.58GiB, Used:13.89GiB
/dev/sda 4.05GiB
/dev/sdb 1.50GiB
/dev/sdc 5.01GiB
/dev/sdd 5.01GiB
/dev/sdf 5.01GiB
/dev/sdg 5.01GiB
System,RAID6: Size:64.00MiB, Used:1.70MiB
/dev/sda 16.00MiB
/dev/sdb 16.00MiB
/dev/sdc 16.00MiB
/dev/sdd 16.00MiB
/dev/sdf 16.00MiB
/dev/sdg 16.00MiB
Unallocated:
/dev/sda 733.65GiB
/dev/sdb 2.15TiB
/dev/sdc 1.02MiB
/dev/sdd 1.02MiB
/dev/sdf 1.02MiB
/dev/sdg 1.02MiB
Can anyone shed some light on why a full balance (sudo btrfs balance
start /mnt/data) doesnt seem to straighten this out? Any and all help
is appreciated.
Thanks!
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