[Linux-cluster] managing GFS corruption on large FS
Patton, Matthew F, CTR, OSD-PA&E
Matthew.Patton.ctr at osd.mil
Wed Nov 29 19:41:33 UTC 2006
Classification: UNCLASSIFIED
> 3. gfs_fsck takes a lot of memory to run, and when it runs
> out of memory,
> it will start swapping to disk, and that will slow it
> down considerably.
> So be sure to run it on a system with lots of memory.
define "lots" please.
> 6. I recently discovered an issue that impacts GFS
> performance for large
> requires approximately 156438 RGs of 256MB each. Whenever GFS
> has to run that linked list, it takes a long time.
> For RHEL5, I'm changing gfs_mkfs so that it picks a more
> intelligent
> RG size based on the file system size,
RG Structures of 4G or 8G seem reasonable to me. Granted I don't know what the RG's do and what all is involved in the housekeeping. 256mb structures probably makes sense up to say 1/4TB volumes. <1/2TB would take 512mb structs and <1TB would be 1G structures. Some quick math and I think you'll see where I'm going with this.
> Unfortunately, there's no way to change the RG size once
> a file system
> has been made. It only happens at gfs_mkfs time.
much like vgcreate.
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