Open-E JovianDSS ver.1.0 up04 Release Notes

Release date: 29.04.2015

Build: 16043

Known issues

Performance tuning

     Sync always for zvol is the safest option and is set by default. However, it can cause write performance decreases since all operations are written and flushed directly to the persistent storage. In case of using sync=always, it is strongly recommended using mirrored write log devices (very fast random writes devices).
     Sync=standard or sync=disabled zvol options provide huge performance improvement but the most recent (up to 5 seconds) cached data can be lost in case of a sudden power failure. Use this option only in environments equipped with UPS.
     For NFS shares the Synchronous data record is enabled by default. This option causes performance to be worse, but data can be safely written. In order to improve the NFS performance you can use Asynchronous data record but in such case, it is strongly recommended to use UPS.

Browser recommendations

     It is strongly recommended to use Mozilla Firefox browser to navigate the system’s GUI. When using other browsers some slight problems with displaying content may occur.

System as a guest in virtual environments

     Hyper-V:
     System doesn't work correctly as a Hyper-V virtual machine (guest). There are issues with hv_netvsc network driver.
 
     VMware ESXi:
     In case of installing the system as a VMware ESXi guest please use the following settings:
       - Guest OS: Other 2.6.x Linux ( 64bit )
       - Number of Cores: 4
       - Memory: Minimum 8GB
       - Network Adapter: VMXNET 3
       - SCSI Controller Type: Paravirtual or LSI Logic SAS
       - Boot Disk : 20GB Thick Provision
       - Add at least 6 virtual disk
       - Edit Settings->Options->Advanced-General->Configuration-> Add row: disk.EnableUUID : TRUE

Reclaim deleted blocks on thin-provisioned LUNs in various systems

     In case of deleting large amounts of data, reclaimed deleted blocks on thin-provisioned LUNs in Windows 2012 can significantly slow down system performance. If you predict frequent deletions of large amounts of data, we recommend turning off the automatic reclaim function in Windows 2012. This can be done by disabling the "file-delete notification" feature in the system registry. To do so, follow the steps below:
       - start Registry Editor.
       - locate the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem       
       - double-click DisableDeleteNotification.
       - in the Value data box, enter a value of 1, and then click OK.
 
     In order to reclaim the free space in Windows 2012 please change the    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem\DisableDeleteNotification key value back to 0 and use "Optimize" tool located in Disc Management->[disk]->Properties->Tools. As the operation can generate a very high load in the system, it is recommended to perform it after-hours.  
In case of VMware ESXi, the automatic reclaim feature is disabled by default. To reclaim the space of deleted blocks on thin-provisioned LUNs, please use vmkfstools. For details, please refer to the VMware Knowledge Base:

For VMware ESXi 5.0: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2014849
For VMware ESXi 5.5 and newer: https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2057513

In case of using Windows 2008 or Citrix Server there is no possibility to reclaim the space released by deleted data of thin-provisioned LUNs.

Deduplication issues and recommendations

     Please be aware that deleting the zvol with deduplication enabled can generate a very high load in the system and lead to unstable behavior. It is strongly recommended to perform such operation only after-hours. To avoid this issue, please use (if possible) single zvol on zpools dedicated for deduplication and delete the zpool which includes the single zvol.
   
     To determine the amount of System RAM required for deduplication, use this formula:
 
                                                                                                                    (Size of Zvol / Volume block size) * 320B / 0.5 / 0.25
 
Where:
320B - is the size of entry in DDT table
0.5 - Percentage of RAM reservation for ARC (50%)
0.25 - Percentage of DDT reservation in ARC (25%)
 
     Example for 1TB data and 64KB Volume block size:
 
                                                                                                       (1099511627776B / 65536B) * 320B / 0.5 / 0.25 = 42949672960B
                                                                                                                        42949672960B / 1024 / 1024 / 1024 = 40GB
 
so for every extra 1TB of storage, system needs extra 40GB RAM.

     Example for 1TB data and 128KB Volume block size:
 
                                                                                                       (1099511627776B / 131072B) * 320B / 0.5 / 0.25 = 21474836480B
                                                                                                                        21474836480B / 1024 / 1024 / 1024 = 20GB
 
so for every extra 1TB of storage, system needs extra 20GB RAM.

IMPORTANT: The above calculations only apply to the worst case scenario, when data is completely unique and will not be deduplicated. For the deduplicable data, the need for RAM drastically decreases. If SSD based Read Cache is present, part of deduplication table will be moved to the SSD and deduplication will work with good performance using less RAM.

Zvols configuration issues and recommendations

     It is strongly recommended to set the client file system block size same as the zvol volume block size. For example, when using 64k zvol volume block size, the Windows Allocation unit size of NTFS should be set to 64k.

Target number limit

    More than 20 targets in the system can cause the Web Browser to demand termination of JavaScript. Please answer "wait".
    In case of more than 60 targets, GUI will not be displayed correctly. This issue will be fixed in the next releases.

Targets with the same name are not assigned correctly

    Having two or more targets with the same name but belonging to various Zpools, will cause that all targets with the same name will be assigned to one Zpool during the import process.

Installation on disks containing LVM metadata

     There is no possibility to install the system on disks containing LVM metadata. You will need to clear those disks before installation. To do so, use the “Remove ZFS data structures and disks partitions” function located in the Extended tools. To access this function, boot the system from a temporary media like a USB drive or DVD.

Import Zpool with broken write log

     There is no option to import Zpool with a broken write log disk using the system’s functions. This is why it is STRONGLY recommended to use mirrored disks for write logs. In case it is necessary to import Zpool with a broken write log, please contact technical support.

Replacing disks in data groups for larger ones can cause your storage license capacity to be exceeded

     In case of replacing damaged disks for larger ones, the size of the entire Zpool will increased. Make sure that the new size will not exceed your purchased storage license.

Periodically after some operations, the GUI needs to be manually refreshed

     After performing some operations, e.g. resilvering, the GUI will show outdated information. In this case refresh the web page manually by pressing F5 on your keyboard. This issue will be fixed in next releases.

Replacing disks in data groups for smaller ones can cause an error and make the disk disappear from the list of available disks

     Operation of replacing a disk in a data group for a smaller one will cause an error "zpool unknown error, exit code 255", and the disk will become unavailable. In order to reuse this disk, please use function "Remove ZFS data structures and disks partitions" located in the Extended tools on the Console screen.

It is strongly recommended to use 64KB or higher Volume block size

     Smaller than 64KB block sizes used with deduplication or read cache will cause very high memory consumption.

RAM recommendations for Read Cache

     To determine how much System RAM is required for Read Cache, use the following formula:

 
                                                                      RAM needed = (Size of Read Cache - reserved size and labels) * bytes reserved by l2hdr structure / Volume block size
 

     For 8KB Volume block size and 1TB Read Cache:

                                                                           RAM needed = (1099511627776B - 4718592B) * 432B / 8192B = 57981809664B
                                                                                                        57981809664B / 1024 / 1024 / 1024 = 54GB
 
Where:
1099511627776B - 1TB Read Cache
4718592B - reserved size and labels
432B - bytes reserved by l2hdr structure
8192B - Volume block size
 
                                                                                                  For 64KB Volume block size and 1TB Read Cache:
                                                                    RAM needed = (1099511627776B - 4718592B) * 432B / 65536B = 7247726208B
                                                                                                       7247726208B / 1024 / 1024 /1024 = 6.75GB


                                                                                                  For 128KB Volume block size and 1TB Read Cache:
                                                                    RAM needed = (1099511627776B - 4718592B) * 432B / 131072B = 3623863104B
                                                                                                       3623863104B / 1024 / 1024 /1024 = 3.37GB

Multiple GUI disk operations may result in an inaccurate available disks list

     Multiple operations of adding and detaching disks from groups can cause that the next operation of detaching will fail, but the disk will be shown on a list of available disks. When trying to add this disk to one group it will fail with the following error "[zfslib-wrap-zpool-ZpoolCmdError-1] invalid vdev specification". In this case, detach this disk once again.

After removing disks from groups they may not be displayed on a list of available disks

     Sometimes after removing disks from groups, Spare/Read Cache/Write Log disks are displayed on a list of unassigned disks, but they are not on a list of available disks. In this case, click the rescan button located in the adding group form.

Reusing disks from an exported and deleted Zpool

     After deleting an exported Zpool, not all disks which were a part of a Zpool become immediately available. Before you can reuse disks, which were previously used as a Spare or a Read Cache, you must first clean them. Use “Remove ZFS data structures and disks partitions” function located in the “Extended tools”.

Negotiated speed of network interfaces may not display correctly

     For some network interfaces, the negotiated speed field may display an incorrect value in GUI and Console. This issue will be fixed in next releases.

Limited possibility to display a large number of elements by the GUI

     After creating multiple snapshots, clones or zvols some forms in GUI work very slow. If you need to create many snapshots, clones or zvols, it is strongly recommended to use CLI in order to perform operations on them.

Open-E VSS Hardware Provider system recommendations

     It is strongly recommended to use Windows Server 2012. On the other Windows systems, Open-E VSS Hardware Provider Configuration works unstable.

Slow WebGUI with more than 100 disks

     Creating, importing and deleting a Zpool with more than 100 disks can take a few minutes or even end up with an error. In such situation, please wait until process will be completed. In case of an error message appeared after creating and deleting processes, please refresh the web page (ctrl-r).

Exceeded quota for dataset does not allow to remove files

     Files located on datasets with exceeded quota cannot be removed. In this case, please resize quota and then remove unnecessary files.

Slow WebGUI with multiple datagroups

     Zpool with more than 20 datagroups causes that some forms on WebGUI work very slow. If you need to create many datagroups, it is strongly recommended to use CLI API.

Slow WebGUI with multiple datasets

     More than 25 datasets cause that WebGUI works slow.

ZFS Upgrade

     For Open-E JovianDSS users, it is recommended to upgrade Zpools to the latest ZFS file system.      Although the file system upgrade is absolutely safe for your data, and takes only few minutes, please be aware that this operation cannot be undone.      In order to upgrade a single Zpool, please use "WebGUI -> Zpool options -> Upgrade file system" from Zpool's option menu.

Intel® Ethernet Controller XL710 Family

     In case of using Open-E JovianDSS with Intel® Ethernet Controller XL710 Family, it is necessary to update firmware’s network controller to the version: f4.33.31377 a1.2 n4.42 e1932.

Web browser’s cache

     After updating from previous versions, some problems with WebGUI content and navigation may occur. To resolve this problems, please clear Web browser cache.

Motherboards with x2APIC technology

     In case of using a motherboard with x2APIC technology enabled, it is necessary to disable x2APIC in BIOS. Otherwise, problems with CPU cores will occur.