Windows 10: Linux - quick way to repair file system (VM or host)

Hi there

Anybody running various flavours of Linux out there whether as VM's or HOST - it seems to me that the most resilient file system is XFS.

On the surprisingly very rare occasions if it breaks ( and when it did it was my fault --"User error" !!) it's easy enough to repair -- even RAID devices. You get an indication when you try and mount a device and you can't mount it because of a message superblock error.

1) ensure relevant device is unmounted or not mounted (lsblk or on red hat type systems ssm list if you install system storage manager). Raid devices are usually /dev/mdx and HDD's usually /dev/sdx.

2) simply run repair_xfs /dev/sdx or /dev/mdx

3) if you get error - journal etc you can re-run with following command

repair_xfs -L /dev/sdx or /devmdx

job done

I had this error on an external USB HDD which I'd unplugged from another system before the HDD was quiesced (my fault). Repaired fine though with the commands above.

When removing devices from VM's ensure quiesced before actually unplugging them - both Windows and Linux have "safely remove devices" feature -- best to use them.

IMO XFS far superior to EXT4 so if in the distro you use if you have a choice of file systems when installing the system or creating file systems on external devices go for XFS rather than EXT4.

Cheers
jimbo

:)

 

Windows HOST, attach Linux external USB to Linux VM


Hi there

I usually run a LINUX HOST for testing Windows VM's - but I need to test some new releases of various Linux distros so I've created some VM's --easy enough and running them on a Windows Host.

However I can't attach a USB drive with a Linux file system (XFS) to the VM as the Windows HOST rejects the HDD wanting me to format it !!. There's 2.7 TB of media files on it - I want to test running media server in a VM.

Anybody know how to bypass the Windows nag prompt about the HDD and be able to attach it direct to the VM.

(The other way round is no problem -- never a problem loading NTFS HDD's on to Linux machines -- however the NTFS file system is SLOW compared with XFS -- on USB3 device on Native windows transfer rate of 1 TB of files from fast NTFS HDD to NTFS USB3 device is max 82 Mib/s - average for whole transfer. On same machine with Native Linux and XFS to XFS (using same HDD's and USB 3 port avg speed is 350 mib/s !! -- HUGE difference !!!).

Note I have to have a Windows Host for this --I know I could run Linux VM's from a Linux Host but in this case I do have to use a Windows Host as that will be the destination system at the end of testing.

BTW I'm running VMWARE workstation 12.1 on W10 Pro Host.

Cheers
jimbo

 

Windows HOST, attach Linux external USB to Linux VM

Not a direct solution but wouldn't it work if drive was formatted as exFAT instead which can be read or written on Linux (may need to add support).

Perhaps putting a small fat 32 partition on drive so you can get drive mounted in vm, and then use tools in vm to read xfs partitions might work?

 

Improve Windows I/O in a VM - from Windows OR Linux Hosts


Hi there

I/O performance is often a problem with Virtual Machines - especially if you are using programs like Vmware with "Virtual" Formatted HDD's such as vdmk - especially with "Bog standard" Spinners..

A better solution by far is if you have the space and 2 HDD's (minimum) available is to pass these through as RAW physical HDD's and then use the NATIVE I/O subsystem of your Guest VM.

For example pass through 2 HDD's from Linux or Windows Hosts to a Windows Guest -- you might be running a Guest VM as a server -- no reason why servers shouldn't be VM's (that way people can access the VM / shared files without touching or even having an account on the HOST at all). Now create Windows Storage spaces from the HDD - this is a very efficient I/O system for Windows and you can set it up as a "Software RAID" type of system. The HDD's don't even have to be of the same size for Windows storage spaces.

If using a Linux Guest from a Windows Host then simply format the 2 HDD's as Ext4 and use the software RAID system in Linux - mdadm.

For Linux Host with Linux VM probably the best way is to simply SHARE the HDD's via Samba and just run the (Virtual) OS from an SSD.

For Windows run the Virtual OS from an SSD - it's the DATA drives I'm concerned with such as file shares for multi-media etc.

Cheers
jimbo