1. Achieving 2.3 GB/s With 16 X 4 TB Drives

    I'm in the process of building a new storage server to replace my 18 TB NAS.

    The server is almost finished, it's now down to adding disk drives. I'm using the HGST 4 TB 7200 RPM drive for this build (SKU 0S03356) (review).

    I have not bought all drives at once, but slowly adding them in smaller quantities. I just don't want to feel too much pain in my wallet at once I guess.

    According to my own tests, this drive has a read/write throughput of 160 MB/s, which is in tune with it's specification.

    So the theoretical performance of a RAID 0 with 16 drives x 160 MB/s = 2560 MB/s. That's over 2.5 gigabytes per second.

    This is the actual real-life performance I was able to achieve.

    root@nano:/storage# dd if=pureawesomeness.dd of=/dev/null bs=1M
    1000000+0 records in
    1000000+0 records out
    1048576000000 bytes (1.0 TB) copied, 453.155 s, 2.3 GB/s

    Personally, 2.3 GB/s is not too shabby in my opinion. Please note that I used a test file of one terabyte, so the 16 GB of RAM my server has, doesn't skew the result.

    This result is very nice, but in practice almost useless. I can saturate dual 10 Gbit NICs with this system, but I don't have that kind of equipment or any other device that could handle such performance.

    But I think it's amazing anyway.

    I'm quite curious how the final 24 drive array will perform in a RAID 0.

    Tagged as : Storage
  2. Affordable Server With Server-Grade Hardware Part II

    If you want to build a home server, it may be advised to actually use server-grade components. I documented the reasons for choosing server-grade hardware already in an earlier post on this topic.

    It is recommended to read the old post first. In this new post, I only show new hardware that could also be chosen as a more modern hardware option.

    My original post dates back to December 2013 and centers around the popular X9SCM-F which is based on the LGA 1155 socket. Please note that the X9SCM-F / LGA 1155 based solution may be cheaper if you want the Xeon processor.

    So I'd like to introduce two Supermicro motherboards that may be of interest.

    Supermicro X10SLL-F Supermicro X10SLL-F

    Some key features are:

    • 2 x Gigabit NIC on-board
    • 6 onboard SATA ports
    • 3 x PCIe (2 x 8x + 1 x 4x)
    • Costs $169 or €160

    This board is one of the cheapest Supermicro boards you can get and it has 3 x PCI-e, which may be of interest if you need to install extra HBA's or RAID cards, SAS expanders and/or network controllers.

    Supermicro X10SL7-F Supermicro X10SL7-F

    This board is about $80 or €90 more expensive than the X10SLL-F but in return, you get eight extra SAS/SATA ports, for a total of 14 SATA ports. With 4 TB drives, this would give you 56 TB of raw storage capacity. This motherboard provides a cheaper solution than an add-on HBA card, which would occupy a PCIe slot. Hoever, the's a caveat: this board has 'only' two PCIe slots. But there's still room for an additional quad-port or 10 Gbe NIC and an extra HBA if required.

    • 2 x Gigabit NIC on-board
    • 6 onboard SATA ports
    • 8 onboard SAS/SATA ports via LSI 2308 chip
    • 2 x PCIe (8x and 4x)
    • Costs $242 or €250

    Overview of CPU's

    CPUPassmark scorePrice in EuroPrice in Dollars
    Intel Pentium G3420 @ 3.20GHz345955 Euro74 Dollar
    Intel Core i3-4130 @ 3.40GHz482794 Euro124 Dollar
    Intel Xeon E3-1230 V3 @ 3.30GHz9459216Euro279 Dollar

    • Dollars are from Newegg, Euro's are from Tweakers.net.
    • Euros are including taxes.
    Tagged as : Supermicro Intel ECC
  3. How to Resolve Extreme Memory Usage on Windows 2008 R2-Based File Servers

    I'm responsible for a file server with about 5 terrabytes of data. The file server is based on Windows 2008 R2. I've noticed extreme memory usage on the server. After a reboot, it slowly builds up until almost all RAM memory is consumed.

    So I googled around and found this post and it turned out I had the same exact issue.

    I've confirmed with the tool 'RAMmap' that NTFS metadata is the issue. Microsoft also created a blog post about this.

    The author of the first article resolved the issue by adding more RAM memory. But with 16 GB already assigned, I was not to happy to add more memory to the virtual file server, eating away on the RAM resources of our virtualisation platform.

    I could never find a root cause of the issue. In that case, you need to obtain the 'Microsoft Windows Dynamic Cache Service'. This application allows you to configure how large the medata caching may grow.

    Please note that this services is not a next-next-finish installation. Follow the included Word document with instructions carefully and configure a sane memory setting for your server. I limited the cache to half the RAM available to the server and this works out well.

    Tagged as : Windows file server
  4. My Experiences With DFS Replication on Windows 2008 R2

    If you are considering implementing DFS replication, consider using Windows 2012 R2 because DFS replication has been massively improved. It supports larger data sets and performance has dramatically been improved over Windows 2008 R2.

    I've implemented DFS replication to keep two file servers synchronised. Click here if or there you want to learn more about DFS itself.

    With DFS, I wanted to create a high-available file server service, based on two file servers, each with their own physical storage. DFS replication makes sure that both file servers are kept in sync.

    If you setup DFS, you need to copy all the data from the original server to the secondary server. This is called seeding and I've used robocopy as recommended by Microsoft in the linked article.

    Seeding is not mandatory. You can just start with an empty folder on the secondary server and just have DFS replicate all files. I've experienced myself that DFS replication can be extremely slow on Windows 2008 R2.

    Once all files are seeded and DFS is configured, the initial replication can still takes days. Replication times are based on:

    1. the number of files
    2. the size of the data
    3. the performance of the disk subsystems of both source and destination

    Note: windows 2012 R2 improves DFS replication dramatically, only more reason to upgrade your file servers to 2012 R2 or higher.

    If you seed the files, DFS will not transfer files if they are identical, thus this saves bandwidth and time. DFS checks if files differ based on their hash. So even if you seed all data, the initial replication can take a while.

    On our virtualised platform, the initial replication of 2.5 GB of data consisting of about five million files took about a full week. To me, that is not a very desirable outcome, but once the initial replication is done, there is no performance issue and all changes are nearly instantly replicated to the secondary server.

    For the particular configuration I've setup, the performance storage subsystem could contribute to the slow initial replication.

    To speed up the replication process, it's important that you install the latest version of robocopy for Windows 2008 R2 on both systems. There is a bug in older versions of robocopy that do not properly set permissions on files. This results in file hash mismatches, causing DFS to replicate all files, nullifying the benefit of seeding.

    Hotfixes for Windows 2008 R2: Hotfixes for Windows 2012 R2:

    To verify if a file on both servers has identical hashes, follow these instructions

    If you've checked a few files and assured that the hashes are identical, it's ok to configure DFS replication. If you see a lot of Event ID 4412 messages in the DFS Replication event log, there probably is an issue with the file hashes.

  5. How Traffic Shaping Can Dramatically Improve Internet Responsiveness

    At work, access to the internet is provided by a 10 Mbit down / 1 Mbit up ADSL-connection. As we are a mid-size company, bandwidth is clearly a severe constraint. But it was not our biggest problem. Even simple web-browsing was very slow.

    As I was setting up a monitoring environment based on Nagios and pnp4nagios, I started to graph the latency of our internet connection, just to prove that we have a problem.

    Boy did we get that proof:

    bad latency

    Just look at the y-axis, which scale is in milliseconds. For most of the day, the average latency is 175 ms, with some high spikes. Just browsing the web was a pain during times of high-latency, which was clearly almost all of the time.

    I became so fed up with our slow internet access that I decided to take matters in my own hands and resolve the low latency issue. The solution? Traffic shaping.

    I learned that as ADSL-connections are saturated, especially their upload capacity, you will experience high latency and packet loss. So the trick is to never saturate the connection.

    I grabbed a Linux box with two network interfaces and placed it between our internet router and our firewall in bridge mode.

    For actual traffic shaping I used wondershaper which is part of Debian or Ubuntu.

    apt-get install wondershaper

    The wondershaper script is extremely simple, it's specifically build to resolve the problem we face with our ADSL connection. It not only prioritises traffic, it allows you to limit bandwidth usage and thus prevent you from saturating the connection.

    This simple example limits bandwidth a bit below full capacity, which dramatically improved latency.


    wondershaper <interface> <rx> <tx>


    wondershaper eth1 9500 700

    As you can see, latency improved dramatically:

    good latency

    Again, look at the y-axis. We went from an average latency of 175 ms to an average of 35 ms. That's quite an improvement.

    Can you spot on which day I implemented traffic shaping?

    week latency

    At the time of writing this blog post, the company is working on fiber internet access, resolving our internet woes, but it will take quite some time before that will be installed, so this is a nice intermediate solution.

    Tagged as : traffic shaping

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