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Creating ext4 file system on a vx volume?

schrammd
Level 5

Long story short, we are trying to utilize block based backups for some 30 million files on a 2 node A/P VCS. Product will not support vxfs, and one of our ideas was to simply keep the vxvm pieces so the scripting and VCS controls all work the same, but simply make the FSs as ext4. I've tried every combination of mkfs and mke2fs commands against a fresh DG and volume, but it never can do it:

mke4fs -F /dev/vx/rdsk/RestoreTarget/RestoreVol2

mke4fs 1.41.12 (17-May-2010)

Warning: could not erase sector 2: Attempt to write block from filesystem resulted in short write

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

Stride=0 blocks, Stripe width=0 blocks

67108864 inodes, 268435456 blocks

13421772 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=4294967296

8192 block groups

32768 blocks per group, 32768 fragments per group

8192 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,

4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,

102400000, 214990848

Warning: could not read block 0: Attempt to read block from filesystem resulted in short read

Warning: could not erase sector 0: Attempt to write block from filesystem resulted in short write

mke4fs: Attempt to write block from filesystem resulted in short write while zeroing block 268435440 at end of filesystem

Writing inode tables: 0/8192

Could not write 7 blocks in inode table starting at 1057: Attempt to write block from filesystem resulted in short write

 

Regardless of the options used, it appears this won't work, so my first question is "should it" and the other is, is there any downside to having VCS managing failover of native LVM/ext4 FS's if this theory cannot pan out?

RHEL5.10, VXSF 5.1+

 

thanks

1 ACCEPTED SOLUTION

Accepted Solutions

schrammd
Level 5

Maybe I have the dense today, but for grins I tried running mkfs.ext4 against the /dev/vx/dsk volume and it worked. I don't understand why this would work but against the /dev/vx/rdsk device would not, yet isn't that the way to do it when creating a vxfs?

Regardless, it can be done and mounted using that method, I just don't totally understand why.

cool

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4 REPLIES 4

mikebounds
Level 6
Partner Accredited

From a SF point of view you should be able to create any filesystem as VxVM just presents a device and I don't see anything in the SF notes about support for any particular fileystems, but the 5.1 vxvm admin guide says vxresize supports ext2 and ext3, so ext2 and ext3 are implicitly supported, so ext4 should work too..

From a VCS point of view, officially the mount agent only supports ext2 and ext3, but ext4 will probably work but you may need to change from the CLI as GUI may not let you enter ext4 for FSType and even the CLI (hares -modify) may not let you enter ext4, in which case you could edit the Mount.xml file in /opt/VRTSvcs/bin/Mount, but changing this file would probably not be officially supported.

If you are having issues using vxvm, then you can use LVM with VCS, but the same issue using ext4 still applies.  ext4 is supported in VCS 6.0, but is not listed for 5.1SP1.

Mike

schrammd
Level 5

hmm, well that is interesting. I wonder what is preventing me from making a FS on there of anything other than vxfs. I didn't try ext2 or ext3 because RedHat specifically said "if we are going to do this, then use ext4", assuming this is because of the performance increases and scalability. Do you know if it would have to be mkfs that creates the FS or should any of the mke* commands work?

thanks

schrammd
Level 5

Maybe I have the dense today, but for grins I tried running mkfs.ext4 against the /dev/vx/dsk volume and it worked. I don't understand why this would work but against the /dev/vx/rdsk device would not, yet isn't that the way to do it when creating a vxfs?

Regardless, it can be done and mounted using that method, I just don't totally understand why.

cool

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mikebounds
Level 6
Partner Accredited

In solaris you create vxfs filesystem using raw rdsk device and it won't work on block device but in linux you can use either the dsk block device or the rdsk device.  For ext filesystem, if I use raw device on RedHat 5.5 I get a warning:

/dev/vx/rdsk/test2dg/vol1 is not a block special device.
Proceed anyway? (y,n)

and it doesn't work if I proceed, so looks like you need to use block device for ext.

In VCS 5.1 I can set FSType to ext4 in the java GUI, but I can't test if it onlines in VCS as RH 5.5 does not have ext4.

Mike