Posts Tagged ‘share’

Scripted CIFS Shares Migration

March 8, 2018

I don’t usually blog about Windows Server and Microsoft products in general, but the need for file server migration comes up in my work quite frequently, so I thought I’d make a quick post on that topic.

There are many use cases, it can be migration from a NAS storage array to a Windows Server or between an on-premises file server and cloud. Every such migration involves copying data and recreating shares. Doing it manually is almost impossible, unless you have only a handful of shares. If you want to replicate all NTFS and share-level permissions consistently from source to destination, scripting is almost the only way to go.

Copying data

I’m sure there are plenty of tools that can perform this task accurately and efficiently. But if you don’t have any special requirements, such as data at transit encryption, Robocopy is probably the simplest tool to use. It comes with every Windows Server installation and starting from Windows Server 2008 supports multithreading.

Below are the command line options I use:

robocopy \\file_server\source_folder D:\destination_folder /E /ZB /DCOPY:T /COPYALL /R:1 /W:1 /V /TEE /MT:128 /XD “System Volume Information” /LOG:D:\robocopy.log

Most of them are common, but there are a few worth pointing out:

  • /MT – use multithreading, 8 threads per Robocopy process by default. If you’re dealing with lots of small files, this can significantly improve performance.
  • /R:1 and /W:1 – Robocopy doesn’t copy locked files to avoid data inconsistencies. Default behaviour is to keep retrying until the file is unlocked. It’s important for the final data synchronisation, but for data seeding I recommend one retry and one second wait to avoid unnecessary delays.
  • /COPYALL and /DCOPY:T will copy all file and directory attributes, permissions, as well as timestamps.
  • /XD “System Volume Information” is useful if you’re copying an entire volume. If you don’t exclude the System Volume Information folder, you may end up copying deduplication and DFSR data, which in addition to wasting disk space, will break these features on the destination server.

Robocopy is typically scheduled to run at certain times of the day, preferably after hours. You can put it in a batch script and schedule using Windows Scheduler. Just keep in mind that if you specify the job to stop after running for a certain amount of hours, Windows Scheduler will stop only the batch script, but the Robocopy process will keep running. As a workaround, you can schedule another job with the following command to kill all Robocopy processes at a certain time of the day, say 6am in the morning:

taskkill /f /im robocopy.exe

Duplicating shares

For copying CIFS shares I’ve been using “sharedup” utility from EMC’s “CIFS Tools” collection. To get the tool, register a free account on https://support.emc.com. You can do that even if you’re not an EMC customer and don’t own an EMC storage array. From there you will be able to search for and download CIFT Tools.

If your source and destination file servers are completely identical, you can use sharedup to duplicate CIFS shares in one command. But it’s rarely the case. Often you want to exclude some of the shares or change paths if your disk drives or directory structure have changed. Sharedup supports input and output file command line options. You can generate a shares list first, which you can edit and then import shares to the destination file server.

To generate the list of shares first run:

sharedup \\source_server \\destination_server ALL /SD /LU /FO:D:\shares.txt /LOG:D:\sharedup.log

Resulting file will have records similar to this:

#
@Drive:E
:Projects ;Projects ;C:\Projects;
#
@Drive:F
:Home;Home;C:\Home;

Delete shares you don’t want to migrate and update target path from C:\ to where your data actually is. Don’t change “@Drive:E” headers, they specify location of the source share, not destination. Also worth noting that you won’t see permissions listed anywhere in this file. This file lists shares and share paths only, permissions are checked and copied at runtime.

Once you’re happy with the list, use the following command to import shares to the destination file server:

sharedup \\source_server \\destination_server ALL /R /SD /LU /FI:D:\shares.txt /LOG:D:\sharedup.log

For server local users and groups, sharedup will check if they exist on destination. So if you run into an error similar to the following, make sure to first create those groups on the destination file server:

10:13:07 : WARNING : The local groups “WinRMRemoteWMIUsers__” and “source_server_WinRMRemoteWMIUsers__” do not exist on the \\destination_server server !
10:13:09 : WARNING : Please use lgdup utility to duplicate the missing local user(s) or group(s) from \\source_server to \\destination_server.
10:13:09 : WARNING : Unable to initialize the Security Descriptor translator

Conclusion

I created this post as a personal howto note, but I’d love to hear if it’s helped anyone else. Or if you have better tool suggestions to accomplish this task, please let me know!

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Permanently map network drive in Windows

May 2, 2012

Have you ever run into an issue when after mapping a network drive and saving login/password you end up with disconnected drive after a reboot? To overcome this problem use command line with the following switches to net use routine:

net use w: \\server\share /savecred /persistent:yes

Then enter your username and password and that seems to be it.

But I had a problem when network drive doesn’t map with error: “Invalid username/password”. Even though they are correct. If you run into a similar problem include username and password into the command like this:

net use w: \\server\share password /savecred /persistent:yes /user:username

Export share in ROCKS

March 14, 2012

In my previous post I described how you can present an iSCSI LUN to a Linux host. I moved all home directories to this NAS share, but later I came to the conclusion that making separate share would be better. Users should have ability to quickly compile applications in their home directories. If home directories are also used as target storage for computational data, then during computation, iSCSI network link can become a bottleneck and slow down everything. That’s why I decided to separate them. It requires exporting additional share and it can be done very easily in ROCKS.

1. Mount the LUN to say /export/scratch

2. Make export by adding (all in one line) to /etc/exports

/export/scratch 192.168.111.128(rw,async,no_root_squash) 192.168.111.0/255.255.255.0(rw,async)

3. Restart nfs

/etc/rc.d/init.d/nfs restart

4. Add line to /etc/auto.share

scratch master.local:/export/&

5. Update 411 config

make -C /var/411

Now share is accessible by all compute nodes from /share/scratch.

Same process is described in ROCKS FAQ here.

Present NetApp iSCSI LUN to Linux host

March 7, 2012

Consider the following scenario (which is in fact a real case). You have a High Performance Computing (HPC) cluster where users usually generate hellova research data. Local hard drives on a frontend node are almost always insufficient. There are two options. First is presenting a NFS share both to frontend and all compute nodes. Since usually compute nodes  connect only to private network for communication with the frontend and don’t have public ip addresses it means a lot of reconfiguration. Not to mention possible security implications.

The simpler solution here is to use iSCSI.  Unlike NFS, which requires direct communication, with iSCSI you can mount a LUN to the frontend and then compute nodes will work with it as ordinary NFS share through the private network. This implies configuration of iSCSI LUN on a NetApp filer and bringing up iSCSI initiator in Linux.

iSCSI configuration consists of several steps. First of all you need to create FlexVol volume where you LUN will reside and then create a LUN inside of it. Second step is creation of initiator group which will enable connectivity between NetApp and a particular host.  And as a last step you will need to map the LUN to the initiator group. It will let the Linux host to see this LUN. In case you disabled iSCSI, don’t forget to enable it on a required interface.

vol create scratch aggrname 1024g
lun create -s 1024g -t linux /vol/scratch/lun0
igroup create -i -t linux hpc
igroup add hpc linux_host_iqn
lun map /vol/scratch/lun0 hpc
iscsi interface enable if_name

Linux host configuration is simple. Install iscsi-initiator-utils packet and add it to init on startup. iSCSI IQN which OS uses for connection to iSCSI targets is read from /etc/iscsi/initiatorname.iscsi upon startup. After iSCSI initiator is up and running you need to initiate discovery process, and if everything goes fine you will see a new hard drive in the system (I had to reboot). Then you just create a partition, make a file system and mount it.

iscsiadm -m discovery -t sendtargets -p nas_ip
fdisk /dev/sdc
mke2fs -j /dev/sdc1
mount /dev/sdc1 /state/partition1/home

I use it for the home directories in ROCKS cluster suite. ROCKS automatically export /home through NFS to compute nodes, which in their turn mount it via autofs. If you intend to use this volume for other purposes, then you will need to configure you custom NFS export.

Old share mapping upon reboot

February 25, 2012

When you change share mapping in users AD logon scripts, for example if you move share to another server, after a reboot users can still see an old path in their drive mappings. Usually it happens if you forget to unmount drive before mounting. If share was already mounted before it won’t remount to a new one. To get rid of that, always add something like net use N: /d /y before mounting line.

However, sometimes it screws up. In case you steel see an old share go to HKEY_CURRENT_USER\ Software\ Microsoft\ Windows\ CurrentVersion\ Explorer\ MountPoints2 and remove cached record for this share. It will look something like ##SERVERNAME#SHARENAME. After that you will hopefully have your share automatically mounted to the correct path.