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Thanksgiving Server Build - DroboPro Questions


NotSleepy
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Happy Thanksgiving.    I am building my latest “homeserver” this thanksgiving weekend.  For most my married life,  extended holiday weekends are the only time that  I am able to work on my servers.   Over the years, I’ve run every version of Windows Server, and of course, Windows HomeServer too.   My “outgoing” homeserver is Windows Server 2012 Essentials,  running on HP Core 2 Duo, 8GB RAM, 5 x 2TB “green” SATA disks.  Three of those disks configured using  Storage Spaces.  Occasionally, one of the disks would “disappear”..  No loss of data.  After the cold shutdown/startup, then all good again.  Then  that same disk completely failed.  Not detected by BIOS.  Again, there was no loss of data, but I found Storage Spaces to be wonky.   Storage Spaces was not ready for “average guy” use.  After replacing the disk, I needed to use power-shell commands to get things right again.    

 

Anyhow, I’ve been collecting parts since the last 4-5 months.  New homeserver is Windows Server 2012 R2 Essentials. I picked up a used  HP Z210 workstation, with XEON E31230 3.20 GHZ processor (8 cores), 32GB RAM.  Also received a used DroboPro with 2 x 2TB Seagate disks.    I have added 2 additional Gigabit NICs.  One NIC dedicated to DroboPro ISCSI (direct connection without switch).   I’ve installed the latest Drobo firmware update. I waited for Black-Friday deals, and I have just purchased 5 x 3TB  WD “Red” disks, which should arrive in a few days.

 

The Thanksgiving  build has been coming along nicely.  No major problems. I have installed the Media Streaming pack.  As of tonight, I’ve got the old server and new server both running on the network.  Note: I used the exact same hostname “HOMESERVER”, and domain name.  Different IP address. .   I’ve performed  successful “test copies” of about 300GB of movies and television shows from old  server to new server.   As soon as I complete migration  my data, (about 2TB),  then I will shutdown the old homeserver.  Then change the IP address of the new server. 

 

Question #1 -  I’ve notice something about the DroboPro.   I’ve monitoring the iSCSI network traffic while running benchmark tests.  When reading from the Drobo, when the test is completed, the network traffic stops.  Then writing to the Drobo, network traffic continues for many minutes after the test is completed.  Strange.  Let’s say that I copy dozen 5GB files to the DroboPro, that might take 5 minutes.  The ISCSI network traffic will continue for about 3-4 minutes.    Any ideas what is happening?

 

Question #2 - I read many blog posts about Drobo poor performance.  I’ve never used a Drobo before, not sure what to expect as peak performance.  I’ve been measuring 120 MB/s  reading and 90-100 MB/s writing.   That seems pretty good.  What level of Read/Write bandwidth is expected for a DroboPro with iSCSI? 

 

---  NotSleepy

 

 

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I suspect the continued traffic is the computer flushing the disk cache - it completes the write to the cache, which is in RAM, and then after the dialog box disappears, continues the write operation to flush out the cache.  Operations like that are why using a UPS can be important.  I'm not certain on that though, but it seems to be the most likely case.

 

Those speeds look like you're saturating the gigabit connection to the Drobo Pro.  120MB is pretty much the max speed, writing being slightly slower makes sense.

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I agree with Andne here, that the issue is the write caching. Though, there may be other things in play here, as well. But it sounds like it's mostly just the write cache.  

And yes, having a UPS is very important here (and in general).

 

 

As for network speed, the max theoretical speed of gigabit networking is 125MB/s, not counting overhead or any other connections.  That you're seeing close to that means that you're saturating the network bus. 

Additionally, for single disk operation, you should expect to see 80-100MB/s speeds, as that is what most HDDs are going to peak at. If the DroboPro is RAIDing the disks, then you may see higher, but that is again limited to the network connection speed.

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NotSleepy, the performance seems quite good. I suspect the direct link for the iSCSI was a good move. I also agree that cache flushing is what you're seeing.

 

I suspect you will have to uninstall & reinstall the Connector on each of your clients.

 

I also think it's a good move to stop using Storage Spaces.

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I suspect you will have to uninstall & reinstall the Connector on each of your clients.

Definitely will. I believe it's a different version between 2012 and 2012R2.

Also, if the clients are joined to the domain.... you may have problems.

 

I also think it's a good move to stop using Storage Spaces.

Any move to stop using Storage Spaces is a good move. There are other solutions (such as StableBit DrivePool and Drive Bender), or you could by a "real" RAID card and just use that. (It will cost you around $200, but a HighPoint RocketRAID card isn't bad, but I'd recommend anything that uses LSI chipsets).
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I suspect the continued traffic is the computer flushing the disk cache - it completes the write to the cache, which is in RAM, and then after the dialog box disappears, continues the write operation to flush out the cache.  Operations like that are why using a UPS can be important.  I'm not certain on that though, but it seems to be the most likely case.

 

Those speeds look like you're saturating the gigabit connection to the Drobo Pro.  120MB is pretty much the max speed, writing being slightly slower makes sense.

 

Andne ---  Yes, I agree.  Since posting my questions, I have found the FAQ for LAN Speed Test - (Totusoft).  They explain write speed vs. read speed, and the Write Cache.     Under my controlled testing, it appears I am getting the best expect bandwidth..    I am starting data migration tonight.   

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I agree with Andne here, that the issue is the write caching. Though, there may be other things in play here, as well. But it sounds like it's mostly just the write cache.  

And yes, having a UPS is very important here (and in general).

 

 

As for network speed, the max theoretical speed of gigabit networking is 125MB/s, not counting overhead or any other connections.  That you're seeing close to that means that you're saturating the network bus. 

Additionally, for single disk operation, you should expect to see 80-100MB/s speeds, as that is what most HDDs are going to peak at. If the DroboPro is RAIDing the disks, then you may see higher, but that is again limited to the network connection speed.

Drashna Jaeire.   Looks like I've scored a "win" with this old used DroboPro. It was sitting in a storage closet for over a year, and my client was about to toss it out in the trash.  I have no experience with Drobo products, so I did not know what level of performance to expect.   Thanks for the great info.  

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NotSleepy, the performance seems quite good. I suspect the direct link for the iSCSI was a good move. I also agree that cache flushing is what you're seeing.

 

I suspect you will have to uninstall & reinstall the Connector on each of your clients.

 

I also think it's a good move to stop using Storage Spaces.

 ikon   -  I had a surplus Gigabit dual port PCI-express card available, and as soon as I scored this old used DroboPro with ISCSI, then I planned to use a direct link for ISCSI.    Looks to be performing excellent.     None of my clients are members of the domain, and none have the Connector installed.     Storage Spaces has much promise, and I don't want to completely give up on it.  it works good as long as you don't suffer a disk failure.  Does anyone know if there are improvements/enhancements in the WSE2012R2 ?   

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The issue with Storage Spaces is that its performance varies greatly depending on which mode you're using it in: mirror, RAID, other. In these forums, some of us say that friends don't let friends drive Storage Spaces. ;)  We feel DrivePool and DriveBender are better options.

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