On 2021-04-21, Kent Watsen wrote:
> - When ZFS is told to use the SSD, it starts the partition
> on sector 256 (not the default sector 34) to ensure good
> SSD NAND alignment.
The OS doesn't get all that close to the NAND layer with typical
computer component SSD drives,
[My previous message was somewhat garbled when reflected back at me. It looks
better in the archives here:
https://marc.info/?l=openbsd-misc=161902769301731=2. I’m resending as
plain-text to see if the problem is on my end.]
I’m running OpenBSD on top of bHyve using virtual disks allocated
I’m running OpenBSD on top of bHyve using virtual disks allocated out of ZFS
pools. While not the same setup, some concepts carry over…
I have two types of pools:
1) an “expensive" pool for fast random IO:
- this pool is made up stripes of SSD-based vdevs.
- ZFS is configured
Christian, Otto, Thanks for your feedback on this one
Ill research it further,
but NTFS has 4K, 8K 32K and 64K Allocation units on the
filessystem and for Microsoft windows running Exchange or Database workloads
they were recommending alignment of the NTFS partitions
on the 1MB offset also.
Tom Smyth:
> if you were to have a 1MB file or a database that needed to read 1MB
> of data, i
> f the partitions are not aligned then
> your underlying storage system need to load 2 chunks or write 2
> chunks for 1 MB of data, written,
You seem to assume that FFS2 would align a 1MB file on
On Wed, Apr 21, 2021 at 09:56:59AM +0100, Tom Smyth wrote:
> Hello Otto, Christian,
>
> I was relying on that paper for the pictures of the alignment issue,
>
> VMFS (vmware file system)since version 5 of vmwarehas allocation
> units of 1MB each
>
> https://kb.vmware.com/s/article/2137120
Hello Otto, Christian,
I was relying on that paper for the pictures of the alignment issue,
VMFS (vmware file system)since version 5 of vmwarehas allocation
units of 1MB each
https://kb.vmware.com/s/article/2137120
my understanding is that SSDs have a similar allocation unit setup of
On Wed, Apr 21, 2021 at 08:20:10AM +0100, Tom Smyth wrote:
> Hi Christian,
>
> if you were to have a 1MB file or a database that needed to read 1MB
> of data, i
> f the partitions are not aligned then
> your underlying storage system need to load 2 chunks or write 2
> chunks for 1 MB of data,
Hi Christian,
if you were to have a 1MB file or a database that needed to read 1MB
of data, i
f the partitions are not aligned then
your underlying storage system need to load 2 chunks or write 2
chunks for 1 MB of data, written,
So *worst* case you would double the workload for the storage
Tom Smyth:
> just installing todays snapshot and the default offset on amd64 is 64,
> (as it has been for as long as I can remember)
It was changed from 63 in 2010.
> Is it worth while updating the defaults so that OpenBSD partition
> layout will be optimal for SSD or other Virtualized RAID
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