Question on multiple pool

[Symadic William]

Hello, I just upgrade my Unraid server from 6.8.3 to 6.9.2

 

I know that there is a new feature to create multiple pools but something I feel confuse.

 

Seems only "Array Device" part got parity check disk?

 

If I create a new pool with 4 disk inside and then set to RAID5, it is a real RAID5? (Because that is no real RAID function in 6.8.3)

And this RAID5 is isolated from the "parity disk" under "Array Device"?

 

Currently I got 10 x 12 TB disks and I would like to break them as follow:

 

POOL1: 4 x 12 TB in RAID5 (i.e. able to lose on disk and recovery)

POOL2: 4 x 12 TB in RAID5 (i.e. able to lose on disk and recovery)

POOL3: 1 x 12 TB

POOL4: 1 x 12 TB

 

So, I only need to do this under "Pool Device" section and totally ignore anything in "Array Device"?

 

Thanks and forgive me if I am asking stupid question, I still a newbie on the new system.

Edited April 21, 2021 by Symadic William

[JorgeB]

Unraid currently only supports one array, pools use btrfs, and can use any of the available btrfs profiles, including raid5/6, but note that those are still considered experimental.

[Symadic William]

Thanks Jorge. Do you mean that such "RAID5" is not that safe 😅?

 

Some forum also say that Btrfs "bugs" cause RAID5/6 not stable

[JorgeB]

1 hour ago, Symadic William said:

Do you mean that such "RAID5" is not that safe 😅?

There are still some issues, but it can be used, I have several btrfs RAID5 pools, but also have good backups.

[Symadic William]

6 hours ago, JorgeB said:

There are still some issues, but it can be used, I have several btrfs RAID5 pools, but also have good backups.

Thanks for your advice 😀

I am now adding  a 4 x 12TB RAID pool 1st, the others will remain as normal array.

 

Anything I need to pay attention on using btrfs RAID5?

[JorgeB]

Monitor the pool for errors, though this is important for any btrfs pool, pool should be immediately scrubbed after any unclean shutdown, but keep in mind that scrub on raid5/6 pools are painfully slow, unless you're using SSDs, so be prepared for that.

[Symadic William]

Thanks Jorge, my parity check is done. However, I found that only "Array Disk" can be add to "Shares".

The "Pool" disk seems cannot be show up in "Shares". Did I missed something?

 

[JorgeB]

Pools are still part of the user shares, any top folder in a pool is a share.

[itimpi]

A pool is (potentially) part of a share when you select that pool within the share setting.   Whether it actually gets used depends on what option you select from the Use cache pool setting.

[Symadic William]

 

I tried to select "only" under  "Use cache pool (for new files/directories)" in "Shares" and now able to access the share folder via SMB.

 

How ever the performance is really terrible @o@"

 

Starting: 110 MB/s then drop down to 30-45 MB /s

 

Is that normal? I am using 10 Gb LAN right now

[JorgeB]

That mostly depends on the hardware used and pool config, I have a 6 disk RAID5 pool and get around 350MB/s sustained writes.

 

 

[Symadic William]

1 hour ago, JorgeB said:

That mostly depends on the hardware used and pool config, I have a 6 disk RAID5 pool and get around 350MB/s sustained writes.

 

 

Feel really strange, I build a single disk pool with one of my SSD, again write speed drop down to 4x MB/s but read speed can keep at 600 MB/s.

How can I check what's going on?

 

My build is:

============

Intel® Core™ i5-9500T CPU @ 2.20GHz

ASRock B365 Phantom Gaming 4
American Megatrends Inc., Version P4.30
BIOS dated: Thu 14 May 2020 12:00:00 AM PDT

32 GB DDR4 Memory

LSI SAS 9207-8i SAS/SATA 6Gb PCI-E 3.0 SAS HBA

WD HC520 12 TB Harddisk x 8

Intel X520-DA2 10Gbs LAN Card
 

 

sydisk-diagnostics-20210423-2136.zip

 

Edited April 23, 2021 by Symadic William

[JorgeB]

Can't download diags, forum problem, what model SSD?

[Symadic William]

2 minutes ago, JorgeB said:

Can't download diags, forum problem, what model SSD?

WD Black SN750 NVMe

 

I tried, no wonder what type of harddisk, array, pool setting, the writing speed keep around 100 MB/s in frist 15-20 second and then drop down to 4XMB /s

 

I uploaded a copy of log file to google drive as follow:

https://drive.google.com/file/d/1y6975SxT02Bg6fzwXbsqE9bspCAKPJEB/view?usp=sharing

 

[JorgeB]

50 minutes ago, Symadic William said:

the writing speed keep around 100 MB/s in frist 15-20 second

This should be much faster with 10GbE, while it's caching to RAM.

 

51 minutes ago, Symadic William said:

and then drop down to 4XMB /s

But this suggests it's not just a network issue, in any case I would start with a single stream iperf test.

[Symadic William]

1 minute ago, JorgeB said:

This should be much faster with 10GbE, while it's caching to RAM.

 

But this suggests it's not just a network issue, in any case I would start with a single stream iperf test.

 

Thanks Jorge, I also hear about iperf from other post, however I don't know how to use it.

 

I downloaded the program to my Win10 PC, seems I need to type some command things.

Another silly question it, in some post, I find that iperf is runnning in Unraid.

 

What should I do in my case? Run from Win10 client PC or Unraid or both 😅?

[JorgeB]

 

[Symadic William]

Many Thanks 😃

 

My information as follow:

 

[JorgeB]

That's not very good, but not what's limiting speeds to <100MB/s, did you try transferring to a disk share to see if it's any different?

[Symadic William]

42 minutes ago, JorgeB said:

That's not very good, but not what's limiting speeds to <100MB/s, did you try transferring to a disk share to see if it's any different?

 

OMG 😶When I activated disk share, the speed write-in changed to around 8X - 100MB/s

How come @@"

[JorgeB]

User shares always have some overhead, though some users feel it much more than others.

[Symadic William]

18 hours ago, JorgeB said:

User shares always have some overhead, though some users feel it much more than others.

Thanks a lot, Jorge 👍

 

I rebuild my RAID5 with original plan (now with disk share), I can now have 4xx - 5xx write-in speed~~~ 😃

 

Never imagine the coding in "User share" will cause much performance issue: https://blog.insanegenius.com/2020/04/25/unraid-user-share-vs-disk-share-smb-performance/