Author Topic: Bad performance? Post here!  (Read 61176 times)

Offline terrastrife

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Re: Bad performance? Post here!
« Reply #135 on: February 13, 2014, 10:45:07 pm »
The parity disk has to verify the parity, hence both read and write actions, this is the slowest part of using energy efficiency mode.
You must remember your physical disk AND the nzfs virtual disk are listed in performance metering, only read one of them.

Im not sure about your views there, the only disk doing both reads and writes is the parity disk, your data disk should be only writing. In performance mode your parity and target data disk will only write, while every dru that uses the parity block space will read.

as for the verify sync, no, you shouldnt see blocks updated as parity is written real time, this isn't snap shot mode. if you see updated block it means a data and parity mismatch.

Offline eeze

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Re: Bad performance? Post here!
« Reply #136 on: February 14, 2014, 12:30:57 am »
The parity disk has to verify the parity, hence both read and write actions, this is the slowest part of using energy efficiency mode.
You must remember your physical disk AND the nzfs virtual disk are listed in performance metering, only read one of them.

Im not sure about your views there, the only disk doing both reads and writes is the parity disk, your data disk should be only writing. In performance mode your parity and target data disk will only write, while every dru that uses the parity block space will read.

as for the verify sync, no, you shouldnt see blocks updated as parity is written real time, this isn't snap shot mode. if you see updated block it means a data and parity mismatch.

Thank you terrastrife, that helps me understand the real-time disk access of the PPU.  I'm thinking I may want to swap out the 3TB RED and put a black in it's place.

I guess I need to run some more copy operations to identify which disks are writing/reading.  In Windows 7 they show up under \device\DRX =  Seems that X is the mapped volume under Flexraid. DR1 = first disk, DR2 = second up to 6 in my case (PPU 1). I can see that under the disk activity monitor.  The disks not in Flexraid I'm able to see the write/reading directly to the disk as (s:\filename.zip, etc)

Good to know. Makes it easier to monitor the activity.

Offline mx5gr

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Re: Bad performance? Post here!
« Reply #137 on: February 14, 2014, 08:02:39 am »
The parity disk has to verify the parity, hence both read and write actions, this is the slowest part of using energy efficiency mode.
You must remember your physical disk AND the nzfs virtual disk are listed in performance metering, only read one of them.

Im not sure about your views there, the only disk doing both reads and writes is the parity disk, your data disk should be only writing. In performance mode your parity and target data disk will only write, while every dru that uses the parity block space will read.

as for the verify sync, no, you shouldnt see blocks updated as parity is written real time, this isn't snap shot mode. if you see updated block it means a data and parity mismatch.

You mention that in energy saver mode, during a write operation "...the only disk doing both reads and writes is the parity disk, your data disk should be only writing..." while in performance mode "...your parity and target data disk will only write, while every dru that uses the parity block space will read".

Under tRAID and the previously discussed SATA Port Multipler utilization, my DRU was on the SATA PM while the PPU is always on an on-board dedicated 6 GBps port. Thus, when writing a file from a DRU that is attached on another dedicated on-board SATA-3 port to the DRU attached to the SATA PM under energy efficient mode, only the PPU and the target DRU should be active. Why then is the write performance limited to around 10 MBps? (without FlexRAID, write performance has been metered to > 70 MBps.

From an earlier Brahim's answer however ( http://forum.flexraid.com/index.php/topic,2735.msg23029.html#msg23029 ) ,"Switch to Energy mode and you will find that the performance does not get any worst". Hence, in either mode, the performance would still be the same, albeit it is clearly stated that the performance degradation in performance mode is due to the simultaneous data read from all DRUs (thus the bottleneck due to the SATA PM)... I am a bit baffled, is there a difference in performance or not?

I am now evaluating RAID-F as suggested by Brahim earlier, better performance due to its design and mode of operation, trying to manage to access network shares through another Windows client, as the share appears, documentation has been followed (wiki etc) however no files or directories of the share (and the storage pool behind it) is reachable. I saw that other users have the same issue in other topics in the forum, as however this issue is non-tRAID related and off-topic, I will not elaborate more on it here.

Offline terrastrife

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Re: Bad performance? Post here!
« Reply #138 on: February 15, 2014, 12:57:32 am »
I'm not sure how to help with this, do you use WD Reds? they seem to have horrendous performance with FlexRAID, that's all I can really think of.

Offline samstudent

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Re: Bad performance? Post here!
« Reply #139 on: February 16, 2014, 12:47:59 am »
I'm getting awful performance, both when copying data to the storage pool and when performing any tasks such as Verify/Sync and creating the parity. When copying to the pool I get around 10 mb/s and when I create the parity the throughput is around 45 mb/s. I'm using 6 Seagate ST3000DM which are 7220 RPM, 64 mb of cache 3 TB drives. I had issues with permissions that I solved by uninstalling and then reinstalling and recreating my array. I'm not sure if that had anything to do with it but I'm just trying to figure out what to do because before I was able to get fairly good speeds at around 100 mb/s copying to the pool. I'm using the default settings in tRaid. Let me know if you anymore information is required.

My system specs:
Windows 7 Ultimate
AMD FX-8320
24 GB of RAM

Offline eeze

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Re: Bad performance? Post here!
« Reply #140 on: February 17, 2014, 03:16:50 am »
I'm not sure how to help with this, do you use WD Reds? they seem to have horrendous performance with FlexRAID, that's all I can really think of.

Hi Terrastrife,

I am indeed using WD Reds, however, if I copy a 100GB (yes 100 gigabyte) file form one drive to another (not in the array) i will get a sustained 145MB/s.  Therefore I don't see how the windows OS caching could possible have anything to do with it as I only have 4GB of memory for that VM. I have a dedicated Highpoint SATA3 card and it's pushing these drives to the limit at 145MB/s (multiple online performance tests confirm these drives run well)

However, when using Flexraid, they drop to 30MB/s.  I've heard about the caching and such, but I think there is more to this than just that (per my above test) -- Not sure how to find out what it is.     

I would like to know if indeed the write operations to the DRU is indeed being limited by the PPU.  If so, how would I test other than buying another HD.

I still wondering on the first page there was talk about copying a file larger than your memory to get the real performance.  Well, I and others have tested large files (100GB in my case) with a 4GB machine and still see sustained speeds of 145MB/s so I cannot believe what's been mentioned here and nobody else has called it out?
« Last Edit: February 18, 2014, 06:42:36 pm by eeze »

Offline dscline

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Re: Bad performance? Post here!
« Reply #141 on: February 17, 2014, 07:55:20 am »
You mention that in energy saver mode, during a write operation "...the only disk doing both reads and writes is the parity disk, your data disk should be only writing..."

I can't say for fact, but I don't THINK this is true.  My server is primarily a media server.  As such, performance isn't critical to me, as long as it meets the minimum performance needed to save and stream media.  The highest need it generally sees is when ripping a blu-ray, and the blu-ray drive doesn't rip much faster than around 20MB/s.  However, I have looked at performance when ripping, and while my ripping software is reporting a read rate of ~20MB/s, I could swear that the target drive AND the two parity drives were ALL reporting around 40MB/s.  My memory could be off, maybe it was just the parity drives reporting that, I'll try to check the next time I rip.

But with that said, even with red drives in my system (though not for parity), I don't have any issues meeting and exceeding at least 20MB/s performance, and I don't have a blazing fast system  (the hardware is 4 years old or more).  10MB/s seems off.
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Offline Marv21

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Re: Bad performance? Post here!
« Reply #142 on: February 18, 2014, 05:40:01 pm »
I got 10MB/s only, too...
I will try now one of these : http://www.ebay.com/itm/NEW-Dell-SAS-SATA-2-0-6Gb-s-8-Port-2x4-PCI-e-HBA-LSISAS2008-IT-/171234527571 .
Neither in Performance or in Energy my Speed get over 10MB/s...
Just using HGST 7200 RPM drives..

I will report later ;)

Offline eeze

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Re: Bad performance? Post here!
« Reply #143 on: February 19, 2014, 07:52:07 am »
Hi Terrastrife,

I am indeed using WD Reds, however, if I copy a 100GB (yes 100 gigabyte) file form one drive to another (not in the array) i will get a sustained 145MB/s.  Therefore I don't see how the windows OS caching could possible have anything to do with it as I only have 4GB of memory for that VM. I have a dedicated Highpoint SATA3 card and it's pushing these drives to the limit at 145MB/s (multiple online performance tests confirm these drives run well)

However, when using Flexraid, they drop to 30MB/s.  I've heard about the caching and such, but I think there is more to this than just that (per my above test) -- Not sure how to find out what it is.     

I would like to know if indeed the write operations to the DRU is indeed being limited by the PPU.  If so, how would I test other than buying another HD.

I still wondering on the first page there was talk about copying a file larger than your memory to get the real performance.  Well, I and others have tested large files (100GB in my case) with a 4GB machine and still see sustained speeds of 145MB/s so I cannot believe what's been mentioned here and nobody else has called it out?

I've been looking around on these forums and although I've seen a few people with WD Reds, i'd say the performance issues are all abound with various disks.

I've tested 2 disks not in the array, yet still on the same controller with the same 100GB file. I've tested from a non-array disk into the array (pools stopped) and from the array to a non-array disk.  Each and every time when the array is involved, the performance is 1/5th of without.

I can only suspect the NZFS driver? I cannot imagine how caching for a 100GB file with a 4GB machine could still come into play.

Looking for some solid feedback here.  I'm really at a loss as to what to do. I'm not willing to sacrifice that speed and i've already paid my $79.   I may have been better with snapshot raid although if i uses the same driver, i may face the same issues.  At a loss here (not just for ideas)

Offline Brahim

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Re: Bad performance? Post here!
« Reply #144 on: February 19, 2014, 08:23:21 am »
@eeze
Did you try the performance mode?
The WD RED have terrible access time making them unsuitable for random operations as done in RAID.

Focus on posting exact figures. Take screenshots of your copy operations showing the a graph. Also, do post screenshots of your RAID statistics page. Use the "Since Last Update" mode to capture a fresh operation.

Getting 30-40MB/s is rather common in energy mode with these high latency disks.
They are one trick ponies. They like to either just read or just write, but don't do well when made to read and write in the same operation.

Offline dscline

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Re: Bad performance? Post here!
« Reply #145 on: February 19, 2014, 08:04:47 pm »
You mention that in energy saver mode, during a write operation "...the only disk doing both reads and writes is the parity disk, your data disk should be only writing..."

I can't say for fact, but I don't THINK this is true... I have looked at performance when ripping, and while my ripping software is reporting a read rate of ~20MB/s, I could swear that the target drive AND the two parity drives were ALL reporting around 40MB/s... I'll try to check the next time I rip.

My memory was good for once.  Ripping a Blu-ray from my client to the server, at the point of this screenshot, my ripping software was reporting around 18MB/s, while the target drive on the server as well as both of the parity drives were reporting a little over twice that.  This is with energy saver mode, the WD2002 drives are the parity:

« Last Edit: February 19, 2014, 08:09:34 pm by dscline »
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Offline terrastrife

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Re: Bad performance? Post here!
« Reply #146 on: February 19, 2014, 09:21:27 pm »
But how much of the above is actual write activity?

Offline dscline

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Re: Bad performance? Post here!
« Reply #147 on: February 20, 2014, 05:53:11 pm »
But how much of the above is actual write activity?
I can't say for fact since the tool I used doesn't break that out, but I would assume about 50%.  Just based on logic, if you are going to update parity when changing the contents of a data unit without reading the contents of the other drives, I would think you would have to first read the existing data to determine what has changed.  For example, if you are going to write 0101 in some location, you first need to read the bits in that same location to determine how much has changed (i.e., if that section was previously 0001, only the 2nd bit needs to change).  So even though you are only writing four bits in this example, there is 8 bits of bandwidth on the data drive (the first read, then the subsequent write).  Once you know what has changed, you know which bits need to be flipped on the parity drive(s).  So you have to read them first to see what they are to start with, then write to flip the changed bits.  You would think that the bandwidth on the parity drives would be lower if it only needs to deal with changed bits rather than all of them, but perhaps you don't realize that benefit due to clustering.  At least that's how I imagine it working in my head, Brahim would have to confirm.  :)  One a related note, you don't really need to see what the data was before if you also read all the other data drives and compute new parity on the fly.  That would eliminate half the bandwidth on the target and parity drive(s), while adding bandwidth on the other drives.  I assume this is kind of what performance mode does.
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Supermicro AOC-SASLP-MV8
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Generic SiI3132

Offline Marv21

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Re: Bad performance? Post here!
« Reply #148 on: February 26, 2014, 02:38:56 pm »
I got 10MB/s only, too...
I will try now one of these : http://www.ebay.com/itm/NEW-Dell-SAS-SATA-2-0-6Gb-s-8-Port-2x4-PCI-e-HBA-LSISAS2008-IT-/171234527571 .
Neither in Performance or in Energy my Speed get over 10MB/s...
Just using HGST 7200 RPM drives..

I will report later ;)

So with my LSI 9211 (IBM 1015 IT flashes) I get with Performance mode 75MB~. Thats not the Write speed of the source disk ( WD GREEN) neither the parity disk (HGST 4TB 7600RPM) , but its better then the 8 MB/s before...

Will report energy in a few minutes.


EDIT1:

With Energy its now at 22MB/s~


Over Ethernet its only 3 MB/s ;/ to the ssd its 120MB/s...
« Last Edit: February 26, 2014, 03:58:39 pm by Marv21 »

Offline Brahim

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Re: Bad performance? Post here!
« Reply #149 on: February 26, 2014, 04:03:48 pm »
So with my LSI 9211 (IBM 1015 IT flashes) I get with Performance mode 75MB~. Thats not the Write speed of the source disk ( WD GREEN) neither the parity disk (HGST 4TB 7600RPM) , but its better then the 8 MB/s before...

Will report energy in a few minutes.

Ah, the difference that a good controller makes. :)