XFS slow performance

XFS slow performance

[Muhammad Fakhrul Rozi Bin Mohd Seth]

Hi All,

I'm using the UBUNTU server with LVM group of SCSI harddisk.

I'm using this setting for XFS:

               1. mkfs.xfs --l logdev=/dev/sda1,size=64m --d agcount=32
                  /dev/test/department

               1. mount -o noatime,nodiratime,nobarrier,logbufs=8
                  /dev/test/department /data/

My current situation is :

1) I'm using XFS file system as my files server
2) i'm using snapshot to make a hot backup like shadow copies in windows

The problem is it takes a long time and some time it make time out for:

1) New file creation
2) Copy files from xfs shared to another local pc's

** what have i check is; if no snapshot was taken; the files sharing was 
go on without problem and really fast.
This problem occurred only when we have a snapshot drives. even a single 
drive.


please help me and advise me on this?

Regards
Rozi



[[HTML alternate version deleted]]

Re: XFS slow performance

[Eric Sandeen]

Muhammad Fakhrul Rozi Bin Mohd Seth wrote:
> Hi All,
...


> ** what have i check is; if no snapshot was taken; the files sharing was 
> go on without problem and really fast.
> This problem occurred only when we have a snapshot drives. even a single 
> drive.
> 
> 
> please help me and advise me on this?

There's not a lot to go on here, but it sounds like it's possibly an lvm
snapshot issue, not an xfs issue, to me.  Can you test another
filesystem temporarily to see if you see the same slowdown when a
snapshot is active?

When a snapshot is active, it's doing copy on write, which will slow
things down to some degree.

-Eric

Re: XFS slow performance

[Eric Sandeen]

Muhammad Fakhrul Rozi Bin Mohd Seth wrote:
> Thanks for the reply;

No problem; please keep the list on cc: so that others with similar
problems will have something to find on google :)

> Yes i have test the other's and it is more worst than XFS.
> So here the snapshot is provide by the LVM not the XFS itself?

That's right; xfs itself has no snapshot capability.  It's done at the
block layer (via lvm in your case).

> Have face any issue on snapshot using LVM before?

I don't use snapshots much so can't say, but they do have overhead.  You
may have more luck asking for suggestions on the lvm users list.  There
might be some tuning you can do.

-Eric

> Regards
> Rozi