Am Sonntag, 5. August 2012 schrieb Stan Hoeppner:
> On 8/5/2012 6:03 AM, Martin Steigerwald wrote:
> > Well the default was 16 AGs for volumes < 2 TiB AFAIR. And it has
> > been reduced to 4 for as I remember exactly performance reasons. Too
> > many AGs on a single device can incur too much parallelity. Thats at
> > least is what I have understood back then.
> For striped md/RAID or LVM volumes mkfs.xfs will create 16 AGs by
> default because it reads the configuration and finds a striped volume.
> The theory here is that more AGs offers better performance in the
> average case on a striped volume.
> With hardware RAID or a single drive, or any storage configuration for
> which mkfs.xfs is unable to query the parameters, mkfs.xfs creates 4
> AGs by default. The 4 AG default has been with us for a very long
> time. It was never reduced.
That does not match my memory, but I´d have to look it up. Maybe next
I am pretty sure mkfs.xfs on a single partition on a single harddisk upto
2 TiB used 16 AGs for quite some time and now uses 4 AGs since quite some
time already. I think I have noted the exact xfsprogs version where it was
changed in my training slides.
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
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