Author Topic: FlexRAID Standards Beta 1  (Read 39588 times)

Offline Hammerfest

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Re: FlexRAID Standards Beta 1
« Reply #15 on: January 05, 2016, 05:47:53 pm »
@Hammerfest

1. You are not supposed to interact with the source disks. So, whatever you are doing is you corrupting your own data. There is nothing to stop you from doing anymore than there is nothing to stop you from pulling a disk and putting into another system and doing all sort of things to it.

2. A disk is failed only if an operation whose failure would corrupt the parity is encountered. You can even pull out a disk and the system will not fail the disk until there is an operation that would compromise parity that is encountered. This is a feature. People have lost data through RAID controllers uselessly dropping disks and forcing user to recover when not needed.

For as long as you don't violate your setup, this approach works perfect. It is flexible and complete.

1/2: I simulated replacing a drive that hardware failed, but in a safe manner IE when the RAID was stopped not started... IE lets say the drive was clicking, it occurs to me since the situation where the unit isnt checked at start/stop, what your saying makes no sense... because I fear pulling a drive while the RAID is started, will it not even notice that a drive has dropped????

3: so I just finished the RAID rebuild/restore operation, THIS TIME, it unmarked them as dropped even gave Success message, but when I try to start the array I get the same message about the disk's "Unable to detect the physical disk representing WD Green 1!
If this disk has failed, please mark it as failed using the Configuration Override feature"

Lets forget how what I did in my message was simply simulating a drive failure at its core and how you disagree with me, and go with #3, I have finished a rebuild, but it still wont start...

I am totally willing to allow you remote control to this system to see for yourself, but I have had NAS devices and WinBlows NAS for the last 10~ years, when I perform specific actions I expect specific results, however I allow for quite a bit of leeway on the specific results such as a simple check/warning when a drive no longer match's the expected configuration...

Offline Brahim

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Re: FlexRAID Standards Beta 1
« Reply #16 on: January 05, 2016, 06:29:16 pm »
@Hammerfest
I read your post a few times and still understand nothing of it.
Your previous post was also confusing but I tried to answer it as best as I could.

You need to start from scratch and re-explain what you are trying to do. Please add screenshots where appropriate as they might help.

Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #17 on: January 05, 2016, 06:52:46 pm »
@Brahim,

Had to rebuild the storage system as my TV cards would not work in vSphere, so now baremetal Server 2012 r2.  Forgot to backup the database before killing the system, upon reinstalling sRAID, and right clicking 'Raid import by scanning' the system has picked out the drives that where in the hybrid raid but dumped them all in to a single Raid 0 instead of the multiple sliced Raid 1/5 config that existed.

I was under the impression from earlier conversations that you had fingerprinted the disks once run in an array so that you could easily get them back by running this command? Did I do it right or have I missed something?

Offline Brahim

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Re: FlexRAID Standards Beta 1
« Reply #18 on: January 05, 2016, 07:00:27 pm »
Hey Benoire,

You cannot import sRAID configuration by scanning the system yet. So, it is important to always to back up the configuration DB for now.

Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #19 on: January 05, 2016, 07:03:13 pm »
Rightio good to know, I'll make sure I do that.  Time to reset the hybrid array... meh takes a bit of time :-(

Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #20 on: January 06, 2016, 02:25:58 am »
@Brahim

Thought I'd check out Raid 5 and play around with the expansion to new disk sizes so I created a new raid 5 array using 2 3tb drives and 1 80GB drive. Once created, I was expecting to see a drive that had a total space of 74GB (usable space from the 80gb) as you'd expect from a normal raid 5 (well that's how I had thought it worked) however in disk management it was showing a 149GB Drive... Also, why is there a difference between what disk management is stating for drive size and what sRAID indicates?

Any chance you can set me straight on this?

Offline Brahim

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Re: FlexRAID Standards Beta 1
« Reply #21 on: January 06, 2016, 09:53:09 am »
@Benoire
This is how RAID 5 actually works. You have 3 disks with the smallest being 75GB. That gives you 75GB x 2 in disk size (1x 75GB is used for parity).

Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #22 on: January 06, 2016, 12:52:10 pm »
Hahahahaha bugger it, I completely screwed up, you're right it does (of course), sorry for the dumb question!

Why does Disk Management show a different drive size to sRAID though?  Its more curiosity than concern, but I did wonder.

Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #23 on: January 06, 2016, 01:34:38 pm »
So now I've got my head around my stupid raid 5 error, I'm playing with upgrading drives.  I've flagged the 75GB as failed and now I am doing a restore from that to a 500Gb drive.  I took the array offline to ensure it would be done quicker, but I'm only getting 12MB/s throughput, and have completed only 1% of the action in 22 minutes.  Is that throughput right?  Is that the right way to swap an existing drive to a larger drive?

Also, I presume you can calculate an estimated completion time for the action based on the actual throughput and dynamically adjust the displayed time?  That might be a nice feature, to get an idea how long the expansion might take?

EDIT: 4 hours and 20 minutes in, its only 20% complete.  All its doing is going from an 80 GB drive to a 500GB with 10GB of data on it. Is this normal?  I recall the synology boxes doing the similar process (using cat /proc/mdstat) but with a throughput of 70-80MB/s.
« Last Edit: January 06, 2016, 05:29:24 pm by Benoire »

Offline Brahim

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Re: FlexRAID Standards Beta 1
« Reply #24 on: January 06, 2016, 06:02:06 pm »
No, that throughput is not normal unless you chose a very small stripe size and kept the rotation level to 1. Only in such case, you are forcing the array to process very small chunks of data at a time.

Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #25 on: January 06, 2016, 06:10:46 pm »
Right, so I left the stripe size and rotation level at the level shown on the screen when I set it up, I assumed that this was an optimum and only required to change it if I knew what I was doing (which I clearly don't :-) )

What would be a good stripe size/rotation level.

Offline Brahim

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Re: FlexRAID Standards Beta 1
« Reply #26 on: January 06, 2016, 06:31:01 pm »
Ah, yeah. We have not gotten to the optimization parts yet. I held off setting the final default values until more data was collected from users.

The optimum stripe size and rotation value depend on the number of disks you have in the system as well as your write profile.

I would say a good blind target would be:
- to set your stripe size and rotation level such that Stripe Size x Rotation Level = 512KB or 1 MB (*)
- and set your stripe size to 128KB or 256KB (*)

(*) benchmark to see which value works best for your setup


Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #27 on: January 06, 2016, 06:33:21 pm »
Cool, I'll have a play with these and see how it improves.

Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #28 on: January 06, 2016, 08:09:09 pm »
Rightio, using log level 4 and stripe size of 256 I've now got around 42MB/s, more to come but a start.

I'm now playing with expanding the array from 3 to four drives.  It stated that this will be done offline.  Is it possible to make this happen online like the Linux based NAS'?  For example, DSM from Synology will allow an online expansion it just takes longer.. Despite this being much quicker than earlier, if I want to expand out to 5 3tb drives from 2 3tb drives & a 1GB Drive, this is likely to take a very long time, certainly longer than is acceptable to keep the array down... Is online expansion something you can do as you have online replacement of drives...

Offline Benoire

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Re: FlexRAID Standards Beta 1
« Reply #29 on: January 06, 2016, 10:18:58 pm »
So, I've hit another issue that might be user related...

I followed the prompts to create a raid migration to a new raid5 setup, in the process adding the 500GB drive... All went well, was much quicker than before (but still not to optimise this)... Once complete, I reset the machine (not sure I needed to but felt it was better to do so) and went in to disk management.

Disk management indicated the right drive size and was fully utilised and formatted as before, but when I go in to explorer it only shows the previous size... Nothing I do makes any difference