Enabling XFS delayed logging (delaylog mount option) might help (see http://en.wikipedia.org/wiki/XFS#Disadvantages). CentOS is (in)famous for using a patched kernel so a kernel upgrade may be needed.
I think you’ve got it right. Make sure you understand and heed the warnings regarding growing RAID 5 in man 8 mdadm. Personally if I were growing an LVM volume, I would not be growing an existing RAID array to do it. I’d create another RAID array, create a new physvol from it, and add … Read more
Splitting the buffer cache is detrimental, but the effect it has is minimal. I’d guess that it’s so small that it is basically impossible to measure. You have to remember that data between different mount points is unshareable too. While different file systems use different allocation buffers, it’s not like the memory is allocated just … Read more
XFS and EL6 have fallen into an ugly state… I’ve abandoned XFS on EL6 systems for the time being due to several upstream features/changes slipping into the Red Hat kernel… This one was a surprise and caused some panic: Why are my XFS filesystems suddenly consuming more space and full of sparse files? Since November … Read more
For straight up Enterprise systems, there is an additional layer in the form of the storage adapter (almost always a RAID card) on which yet another layer of cache exists. There is a lot of abstraction in the storage stack these days, and I went into deep detail in this in a blog series I … Read more
Verification is a tricky one. My first thought was to do a series of direct-IO 4KB reads from the media and watch the blinkin-lights. If every xth read causes two drives to flash, it’s a sign of misalignment (4kb read just spanned a RAID stripe boundary). However, you’re 3000 odd miles away from the hardware … Read more
I want to extend suggestions above. It is extremly worth setting up overlay block device, so any changes to the file system that you’ll do in attempt to recover it will not change anything on the RAID and this will allow you to reset everything and start from the beginning. Therefore, you’ll be given infinite … Read more
You can make a backup, and then create a new smaller file system and restore. XFS cannot be shrunk (ref).
ZFS on linux is unfortunately still not a viable solution, even if you dismiss the issue of being a FUSE module (which can seriously cramp performance on certain workloads). It simply isn’t complete enough. Also, I don’t think there’s a debugfs for ZFS on linux, which is a serious negative. debugfs is the traditional name … Read more
You can do this without any problems… I’m assuming /dev/sdb is a separate HP Smart Array Logical Drive. Don’t use any partitioning for this setup… Just create the filesystem on the block device: mkfs.xfs -f -l size=256m,version=2 -s size=4096 /dev/sdb When you want to expand at a later date, add disks and expand the HP … Read more