… raid-10 + LVM, making sure to stripe the LV when we need to and align the partition correctly. We got decent tpcc… data will compress much more. That gives us much more disk space than we expected so even more snapshots! Integrity With… from the other drive in the mirror. Better availability and disk usage On purpose, I allocated mirror pairs using drives from…
Post: Aligning IO on a hard disk RAID – the Theory
June 9, 2011 By 18 Comments
… you want to align IO to a stripe element as you may otherwise end up reading or writing to more disks than you… a single disk because of the alignment to a stripe unit. In the second example however every other page spans two disks so there… file systems let you set stripe width and stripe unit size so they can do a proper alignment based on that. Mind however…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 13 Comments
… can we get from a proper IO alignment on a 4-disk RAID1+0 with 64k stripe element. I haven’t been running… not aware that it is not aligned to the beginning of the stripe element. 3. 1M alignment in partition table but no options… – random reads and random writes – IO alignment on a 4-disk RAID10 with standard 64k stripe element size makes a significant difference. When…
Post: Setting up XFS on Hardware RAID -- the simple edition
December 16, 2011 By 9 Comments
… only when needed. Aligning the Partitions Once you have the partitions, it could look something like this: #fdisk -ul Disk /dev/sda… that it is aligned with the RAID stripes? It takes a small amount of math: Start with your RAID stripe size. Let’s…. We need to know two things: RAID stripe size Number of unique, utilized disks in the RAID. This turns out to be…
Comment: Setting up XFS on Hardware RAID -- the simple edition
December 18, 2011 By 9 Comments
… by default on mkfs.xfs. @Nate, The idea behind stripe size is aligned I/O (It is not just XFS which allows…* allow it too) , if you have restriped and added/removed disks, you can specify different sunit/swidth to mount for xfs… and existing data will be unaligned but new data will aligned. So better in this case is to backup your fs…
