Date: Thu, 6 Nov 2014 15:58:46 +0100 From: Borja Marcos <borjam@sarenet.es> To: Steven Hartland <killing@multiplay.co.uk> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS bug: was creating ZIL ignores vfs.zfs.min_auto_ashift, should be ZIL sets improper ashift with AHCI controllers Message-ID: <21D2A3A9-B6C1-458F-B17F-480251E999AE@sarenet.es> In-Reply-To: <545B76EF.6050709@multiplay.co.uk> References: <B731A922-3F83-4D8E-A4EA-22C5CA8A3850@sarenet.es> <9C91F97841BC4347910F206618BAA3BB9AF327D1@PAIMAIL.pai.local> <545B76EF.6050709@multiplay.co.uk>
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On Nov 6, 2014, at 2:26 PM, Steven Hartland wrote:
> That's not relevant as min when set should override the drives params
There is more to this than it seems, I just found more funny stuff.=20
MY CONCLUSION IS: when creating a ZIL device, it behaves differently =
depending on the disk controller. It works with SAS,
and it doesn't work with AHCI.
When using an AHCI controller, ZIL ignores *both* the 4K block quirk and =
the min_auto_ashift variables. Ashift is fixed to 9. It only
uses a different ashift when using a "nop" device. For example, I have =
tried with a 4 KB gnop device and this time it used the correct ashift, =
12.
When using a SAS controller, ZIL works perfectly with both.
Seems quite odd to me. I am not running exactly the same version on both =
machines (the one with AHCI controllers is running -STABLE
from three days ago) and the one with the SAS controller is running =
10.1-RC4. But the results should be the same.
I've added the relevant quirk to ata_da.c and the SSD is now
properly "quirked":
ada1 at ahcich1 bus 0 scbus1 target 0 lun 0
ada1: <INTEL SSDSA2CT040G3 4PC10362> ATA-8 SATA 2.x device
ada1: Serial Number PEPR408501DV040AGN
ada1: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
ada1: Command Queueing enabled
ada1: 38166MB (78165360 512 byte sectors: 16H 63S/T 16383C)
ada1: quirks=3D0x1<4K>
But still something is wrong:
EXAMPLE ONE: AHCI controller, min_auto_ashift with the default value of =
9.
The log child, has the wrong ashift, 9, regardless of the 4K quirk.
children[1]:
type: 'disk'
id: 1
guid: 2447450905312007897
path: '/dev/ada1'
phys_path: '/dev/ada1'
whole_disk: 1
metaslab_array: 0
metaslab_shift: 0
ashift: 9
asize: 40015757312
is_log: 1
create_txg: 11741519
EXAMPLE 2: AHCI controller, raise min_auto_ashift to 12
# sysctl vfs.zfs.min_auto_ashift=3D12
vfs.zfs.min_auto_ashift: 9 -> 12
# zpool add rpool log ada1
And our log child still has the wrong ashift.
children[1]:
type: 'disk'
id: 1
guid: 17598938711972588792
path: '/dev/ada1'
phys_path: '/dev/ada1'
whole_disk: 1
metaslab_array: 0
metaslab_shift: 0
ashift: 9
asize: 40015757312
is_log: 1
create_txg: 11741560
EXAMPLE 3: Doing the same as example one, but using a SAS controller =
(mps).
I haven't changed the min_auto_ashift.
da3: <ATA Samsung SSD 840 BB0Q> Fixed Direct Access SCSI-6 device=20
da3: Serial Number S1D9NEADA08568E =20
da3: 600.000MB/s transfers
da3: Command Queueing enabled
da3: 953869MB (1953525168 512 byte sectors: 255H 63S/T 121601C)
da3: quirks=3D0x8<4K>
da1: <ATA Samsung SSD 840 BB0Q> Fixed Direct Access SCSI-6 device=20
da1: Serial Number S1D9NEADA08549F =20
da1: 600.000MB/s transfers
da1: Command Queueing enabled
da1: 953869MB (1953525168 512 byte sectors: 255H 63S/T 121601C)
da1: quirks=3D0x8<4K>
da2: <ATA Samsung SSD 840 BB0Q> Fixed Direct Access SCSI-6 device=20
da2: Serial Number S1D9NEADA08548T =20
da2: 600.000MB/s transfers
da2: Command Queueing enabled
da2: 953869MB (1953525168 512 byte sectors: 255H 63S/T 121601C)
da2: quirks=3D0x8<4K>
Now, we create a pool. I did this in two steps in order to reproduce my =
AHCI more accurately.
# zpool create sample mirror da2 da3
and add a log device
# zpool add sample log da1
And our log device uses the ashift...
children[1]:
type: 'disk'
id: 1
guid: 1327562712929751294
path: '/dev/da1'
phys_path: '/dev/da1'
whole_disk: 1
metaslab_array: 38
metaslab_shift: 33
ashift: 12 <=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D BINGO! 12!!
asize: 1000199946240
is_log: 1
create_txg: 7
EXAMPLE 4: Same hardware as before, but I have compiled a "dequirked" =
kernel. The Samsung 840 SSD is now
detected with 512 byte sectors.
# sysctl vfs.zfs.min_auto_ashift=3D12
# zpool create sample da2 da3
# zpool add sample log da1
# zdb
sample:
version: 5000
name: 'sample'
state: 0
txg: 10
pool_guid: 10244789911221894670
hostid: 1065071139
hostname: 'elibm'
vdev_children: 3
vdev_tree:
type: 'root'
id: 0
guid: 10244789911221894670
create_txg: 4
children[0]:
type: 'disk'
id: 0
guid: 147759032286414284
path: '/dev/da2'
phys_path: '/dev/da2'
whole_disk: 1
metaslab_array: 37
metaslab_shift: 33
ashift: 12
asize: 1000199946240
is_log: 0
create_txg: 4
children[1]:
type: 'disk'
id: 1
guid: 2632519121370708463
path: '/dev/da3'
phys_path: '/dev/da3'
whole_disk: 1
metaslab_array: 34
metaslab_shift: 33
ashift: 12
asize: 1000199946240
is_log: 0
create_txg: 4
children[2]:
type: 'disk'
id: 2
guid: 10136980984141171426
path: '/dev/da1'
phys_path: '/dev/da1'
whole_disk: 1
metaslab_array: 39
metaslab_shift: 33
ashift: 12 =
<=3D=3D=3D=3D=3D=3D=3D=3D=3D 12, ashift for the log device
asize: 1000199946240
is_log: 1
create_txg: 8
features_for_read:
com.delphix:hole_birth
com.delphix:embedded_data
root@elibm:~ #=20
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