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Re: Balance - Find out how long?

BaJohn
Virtuoso

Balance - Find out how long?

Being new to ReadyNAS there were various things I wanted to know.
Of these was how long did each of the 'volume scheduled options' take to run.
I have already raised posts about Data Scrubbing, Defrag and Disk Test (See bottom of this post).
The last of these is the Balance process and how long it takes to run.

My Newbie interpretation is that Balancing is carried out at the BTRFS level, and although originally envisaged for multi disk file systems, still has some benefits on single disk file systems.
Space is balanced between the data and metadata, and if there is damaged replication on a RAID system, then the RAID itself can be utilized to rebuild the damaged information.
There is far more details of this elsewhere, and I only wanted to provide a brief overview of the functionality.

Having trawled through the forums, one thing is clear. Balancing should be carried out when the data on the ReadyNAS is small and be carried out regularly.
If left until the volume(s) are getting full, it can take a very long time (9 hours in one post, with severe fragmentation and near full disk).
However, balancing MAY help solve "No space left on device" as this quote (by an expert) pinched from another post indicates.
"Space is allocated to data and to metadata. As the allocation is used up for either of these free space is allocated as needed. However when there is no more unallocated space you can run out of space allocated to data or to metadata even when there is plenty of free space in the other. A balance can be used to address this."

The amount of time Balancing takes depends on how much data is used, how full and how fragmented the system is.
I am unclear on this, but it MAY also depend on what RAID level is being used.

I have now done a few balances and intend to do them regularly every few weeks.
The data below MAY be useful to new persons such as myself and help people with their expectations.
So I suggest that those who are interested provide their information in this post.

System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments
RN516 ...... 6.2.2 .... 10 ....... 6 of 4 TB .... 10.90 TiB ... 1.52 TiB ..... < 2 Mins ......... 9, 11, 14, 26 secs and 1 min 15 secs.
RN316 ...... 6.2.2 ..... 6 ....... 5 of 4 TB ..... 10.90 TiB ... 6.4 TiB ...... 2 Mins ........... Taken from another post indicating a much fuller system.
Pro-6 ....... 6.2.3 ..... 5 ....... 3 of 3 TB ...... 5.45 TiB ... 2.08 TiB ..... < 2 Mins ......... Beta T1773 - 1 min 22 secs and 54 secs.
RN202 ...... 6.3.3 .... jbod .... 2 of 3 TB ...... 5.45 TiB ... 2.63 TiB ..... < 2 min. ........ Two separate jobs, one for each jbod volume.




PLEASE ADD YOUR DATA TO THIS POST

I believe that a lot of ReadyNAS users have carried out Balancing, some taking far more than 2 mins.
IMHO it is unwise to wait until your system is near full capacity before doing a Balance.
If done regularly the time to run will be minimized.

Please note I am not a ReadyNAS expert, just a Newbie wishing to collate information for the good of all.

Defrag - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=21&t=80004
NAS Disk Test - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=11&t=79874
Data Scrubbing - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=11&t=79865
Message 1 of 9
chainlinc
Guide

Re: Balance - Find out how long?

My addition:

System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments
Pro-6 ...... 6.2.3 .... 5 ....... 3 of 3 TB .... 5.45 TiB ..... 2.03 TiB ..... 1:22 Mins ........ Beta T1773
Message 2 of 9
chainlinc
Guide

Re: Balance - Find out how long?

I did it again:

System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments
Pro-6 ...... 6.2.3 .... 5 ....... 3 of 3 TB .... 5.45 TiB ..... 2.14 TiB ..... 54 Secs ........ Beta T1773

and to be clear, when I posted '1:22 Mins', it meant 82 Secs NOT 82 Mins.
Message 3 of 9
ljung
Tutor

Re: Balance - Find out how long?

System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments
RN202 ...... 6.3.3 .... jbod .... 2 of 3 TB ..... 5.45 TiB ..... 2.63 TiB .... < 2 min. ........ two separate jobs, one for each jbod volume.


have not run a balance on my RN104 with 4x1TB raid5 yet.
Message 4 of 9
JGwilliam
Guide

Re: Balance - Find out how long?

Hi, some of this is from memory, it's over the past 4 to 6 weeks, so on four different weekends, we started looking into balance, defrag, scrub after performance issues with an application that uses flat files and does a lot R/W to the NAS (the app doesn't like isci, needless to say trying to get rid of it).

 

System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments

A RN3220 ...... 6..2.4 .... 6.... 6 of 3 TB ...... 10.8 TB ... 9 TB ..... 36 hours. ........ First time running it, Hosted VMs unusable

A RN3220 ...... 6..2.4 .... 6.... 6 of 3 TB ...... 10.8 TB ... 8 TB ..... 18 hours. ........ Second time after clearing up space, hosted VMs bearable

A RN3220 ...... 6..2.4 .... 6.... 6 of 3 TB ...... 10.8 TB ... 0.5 TB ..... cancelled after 36 hours. ........ Third time as forgot to cancel scheddule. We actually cleared up some snapshots whilst it was balancing, which meant it got confused. When we cancelled it, it was at about 208%. Hosted VMs unusable

A RN3220 ...... 6..2.4 .... 6.... 6 of 3 TB ...... 10.8 TB ... 2.63 TB ..... 5 hours. ........ Fourth time, all VMs off so don't know impact 

 

B RN3220 ...... 6..2.4 .... 10.... 6 of 3 TB ...... 8 TB ... 1 TB ..... 25 min. ........ Never done before

B RN3220 ...... 6..2.4 .... 10.... 6 of 3 TB ...... 8 TB ... 1 TB ..... <30 min. ........ Weekly schedule now varies between <5 and <30

 

We're due to upgrade the OS this week on both systems which may make a difference.

Some of our systems on System A are required 16 hours a day, 7 days a week, so finding downtime to run an 8 hour process is difficult. When I've got stats for defrag/scrub i'll add them to the other post. We're also planning to increase TB and flatten System A to RAID 10 as the performance is so much better, but not til Jan

 

They key things I can tell from this are A) clear up any space before balancing not during, B) RAID 10 balances more efficiently than X-RAID 6, C) have it as part of your implementation plan, not an afterthought!

 

Hope this helps with the info

Jo

Message 5 of 9
JGwilliam
Guide

Re: Balance - Find out how long?

Sorry, don't know how to edit my previous post, I mixed up used and free on system B

 

System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments

B RN3220 ...... 6..2.4 .... 10.... 6 of 3 TB ...... 8 TB ... 7 TB ..... 25 min. ........ Never done before

B RN3220 ...... 6..2.4 .... 10.... 6 of 3 TB ...... 8 TB ... 7 TB ..... <30 min. ........ Weekly schedule now varies between <5 and <30

Message 6 of 9
Retired_Member
Not applicable

Re: Balance - Find out how long?

I have a ReadyNAS 3130 (Firmware 6.4.0) with Data of 6.39TB and 9.97TB free in a RAID 5.  Balance is at 10% and on DAY 3....its causing all types of issues, none of my backups to the NAS are working and tons of alrams (about NAS disconnects) from Veeam One.

 

This is the first time I clicked Balance, but with my free space I didnt think I was going to have any issues.

 

 

Message 7 of 9
StephenB
Guru

Re: Balance - Find out how long?

On my RN102 I have two 3 TB jbod volumes.  I deleted about 500 GB of snapshots on one drive, the other drive didn't use a lot of snapshot space.

 

The drive with the deleted snapshots took about 30 hours to balance.  The other drive took 20 minutes.

 

How long the balance takes depends on the amount of unused space btrfs finds in the allocated chunks.  If the unused space in a chunk is less than a threshold (which I think is set to 61% in 6.4.0) it is skipped.  If it is greater than the threshold, then the balance reclaims the space (which is what takes the time).

 

So the running time depends on the deletions you've done since the previous balance - deletions of snapshots if you have them on, normal deletions if you don't.  The RAID level of course can impact performance generally - it doesn't impact balancing specifically.

Message 8 of 9
JGwilliam
Guide

Re: Balance - Find out how long?

Hi, here are some updated stats, we've spent time over new year putting in additional drives and changing the partitions, so we have a RAID10 partition that we use for iscsi connections and clustered storage. And a RAID1 partition that we use for backup so lots of data changing daily.

 

System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments

A RN3220 . 6...4.1 .... 10.... 6 of 3 TB ...... 8 TB .........6 TB ..... 2 min. ........ Weekly

A RN3220 . 6...4.1 .... ..1.... 2 of 3 TB ...... 3 TB ... ..... 2TB ..... 10 min. ........ Weekly

 

B RN3220 . 6...4.1 .... 10.... 6 of 3 TB ...... 8 TB ... .....6 TB ..... 1 min. ........ Weekly

B RN3220 . 6...4.1 .... ..1.... 2 of 3 TB ...... 3 TB ...  .....1TB ..... 2 min. ........ Weekly

 

Message 9 of 9
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