Testing ZFS with XCP-ng

borzel

@olivierlambert My biggest Question: Why is this not a good Idea?

How do big datacenters solve the issue with the performance? Just install on Hardware? With virtual Appliance you are limited to GBit speed.

I run more than one XO's, one for Backups and one for Useraccess. Don't want users on my Backupserver.

Maybe this is something for a separat thread...

olivierlambert

VM speed is not limited to GBit speed. XO proxies will deal with big infrastructures to avoid bottlenecks.

borzel

@olivierlambert ah, ok

borzel

I did a little more testing with ZFS, tried to move a disk from localpool to srpool

Setup

XCP-ng on single 500Gb disk, ZFS-Pool created on a separat partition on that disk (~420GB) -> localpool -> SR named localzfs
ZFS-Pool on 4 x 500GB Disks (Raid10) -> srpool -> SR named sr1

Error

0_1530972133820_4eefffb1-2464-4985-a46d-da41cc6403b3-grafik.png

Output of /var/log/SMLog

 Jul  7 15:44:07 xen SM: [28282] ['uuidgen', '-r']
 Jul  7 15:44:07 xen SM: [28282]   pread SUCCESS
 Jul  7 15:44:07 xen SM: [28282] lock: opening lock file /var/lock/sm/4c47f4b0-2504-fe56-085c-1ffe2269ddea/sr
 Jul  7 15:44:07 xen SM: [28282] lock: acquired /var/lock/sm/4c47f4b0-2504-fe56-085c-1ffe2269ddea/sr
 Jul  7 15:44:07 xen SM: [28282] vdi_create {'sr_uuid': '4c47f4b0-2504-fe56-085c-1ffe2269ddea', 'subtask_of':      'DummyRef:|62abb588-91e6-46d7-8c89-a1be48c843bd|VDI.create', 'vdi_type': 'system', 'args': ['10737418240', 'xo-os', '', '', 'false', '19700101T00:00:00Z', '', 'false'], 'o_direct': False, 'host_ref': 'OpaqueRef:ada301d3-f232-3421-527a-d511fd63f8c6', 'session_ref': 'OpaqueRef:02edf603-3cdf-444a-af75-1fb0a8d71216', 'device_config': {'SRmaster': 'true', 'location': '/mnt/srpool/sr1'}, 'command': 'vdi_create', 'sr_ref': 'OpaqueRef:0c8c4688-d402-4329-a99b-6273401246ec', 'vdi_sm_config': {}}
 Jul  7 15:44:07 xen SM: [28282] ['/usr/sbin/td-util', 'create', 'vhd', '10240', '/var/run/sr-mount/4c47f4b0-2504-fe56-085c-1ffe2269ddea/11a040ba-53fd-4119-80b3-7ea5a7e134c6.vhd']
 Jul  7 15:44:07 xen SM: [28282]   pread SUCCESS
 Jul  7 15:44:07 xen SM: [28282] ['/usr/sbin/td-util', 'query', 'vhd', '-v', '/var/run/sr-mount/4c47f4b0-2504-fe56-085c-     1ffe2269ddea/11a040ba-53fd-4119-80b3-7ea5a7e134c6.vhd']
 Jul  7 15:44:07 xen SM: [28282]   pread SUCCESS
 Jul  7 15:44:07 xen SM: [28282] lock: released /var/lock/sm/4c47f4b0-2504-fe56-085c-1ffe2269ddea/sr
 Jul  7 15:44:07 xen SM: [28282] lock: closed /var/lock/sm/4c47f4b0-2504-fe56-085c-1ffe2269ddea/sr
 Jul  7 15:44:07 xen SM: [28311] lock: opening lock file /var/lock/sm/319aebee-24f0-8232-0d9e-ad42a75d8154/sr
 Jul  7 15:44:07 xen SM: [28311] lock: acquired /var/lock/sm/319aebee-24f0-8232-0d9e-ad42a75d8154/sr
 Jul  7 15:44:07 xen SM: [28311] ['/usr/sbin/td-util', 'query', 'vhd', '-vpfb', '/var/run/sr-mount/319aebee-24f0-8232-0d9e-ad42a75d8154/ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0.vhd']
 Jul  7 15:44:07 xen SM: [28311]   pread SUCCESS
 Jul  7 15:44:07 xen SM: [28311] vdi_attach {'sr_uuid': '319aebee-24f0-8232-0d9e-ad42a75d8154', 'subtask_of': 'DummyRef:|b0cce7fa-75bb-4677-981a-4383e5fe1487|VDI.attach', 'vdi_ref': 'OpaqueRef:9daa47a5-1cae-40c2-b62e-88a767f38877', 'vdi_on_boot': 'persist', 'args': ['false'], 'o_direct': False, 'vdi_location': 'ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0', 'host_ref': 'OpaqueRef:ada301d3-f232-3421-527a-d511fd63f8c6', 'session_ref': 'OpaqueRef:a27b0e88-cebe-41a7-bc0c-ae0eb46dd011', 'device_config': {'SRmaster': 'true', 'location': '/localpool/sr'}, 'command': 'vdi_attach', 'vdi_allow_caching': 'false', 'sr_ref': 'OpaqueRef:e4d0225c-1737-4496-8701-86a7f7ac18c1', 'vdi_uuid': 'ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0'}
 Jul  7 15:44:07 xen SM: [28311] lock: opening lock file /var/lock/sm/ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0/vdi
 Jul  7 15:44:07 xen SM: [28311] result: {'o_direct_reason': 'SR_NOT_SUPPORTED', 'params': '/dev/sm/backend/319aebee-24f0-8232-0d9e-ad42a75d8154/ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0', 'o_direct': True, 'xenstore_data': {'scsi/0x12/0x80': 'AIAAEmNhODhmOGRjLTRhYjYtNGIgIA==', 'scsi/0x12/0x83': 'AIMAMQIBAC1YRU5TUkMgIGNhODhmOGRjLTRhYjYtNGJlNy05MDg0LTFiNDFjYmM4YzFjMCA=', 'vdi-uuid': 'ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0', 'mem-pool': '319aebee-24f0-8232-0d9e-ad42a75d8154'}}
 Jul  7 15:44:07 xen SM: [28311] lock: closed /var/lock/sm/ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0/vdi
 Jul  7 15:44:07 xen SM: [28311] lock: released /var/lock/sm/319aebee-24f0-8232-0d9e-ad42a75d8154/sr
 Jul  7 15:44:07 xen SM: [28311] lock: closed /var/lock/sm/319aebee-24f0-8232-0d9e-ad42a75d8154/sr
 Jul  7 15:44:08 xen SM: [28337] lock: opening lock file /var/lock/sm/319aebee-24f0-8232-0d9e-ad42a75d8154/sr
 Jul  7 15:44:08 xen SM: [28337] lock: acquired /var/lock/sm/319aebee-24f0-8232-0d9e-ad42a75d8154/sr
 Jul  7 15:44:08 xen SM: [28337] ['/usr/sbin/td-util', 'query', 'vhd', '-vpfb', '/var/run/sr-mount/319aebee-24f0-8232-0d9e-ad42a75d8154/ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0.vhd']
 Jul  7 15:44:08 xen SM: [28337]   pread SUCCESS
 Jul  7 15:44:08 xen SM: [28337] lock: released /var/lock/sm/319aebee-24f0-8232-0d9e-ad42a75d8154/sr
 Jul  7 15:44:08 xen SM: [28337] vdi_activate {'sr_uuid': '319aebee-24f0-8232-0d9e-ad42a75d8154', 'subtask_of': 'DummyRef:|1f6f53c2-0d1e-462c-aeea-5d109e55d44f|VDI.activate', 'vdi_ref': 'OpaqueRef:9daa47a5-1cae-40c2-b62e-88a767f38877', 'vdi_on_boot': 'persist', 'args': ['false'], 'o_direct': False, 'vdi_location': 'ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0', 'host_ref': 'OpaqueRef:ada301d3-f232-3421-527a-d511fd63f8c6', 'session_ref': 'OpaqueRef:392bd2b6-2a84-48ca-96f1-fe0bdaa96f20', 'device_config': {'SRmaster': 'true', 'location': '/localpool/sr'}, 'command': 'vdi_activate', 'vdi_allow_caching': 'false', 'sr_ref': 'OpaqueRef:e4d0225c-1737-4496-8701-86a7f7ac18c1', 'vdi_uuid': 'ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0'}
 Jul  7 15:44:08 xen SM: [28337] lock: opening lock file /var/lock/sm/ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0/vdi
 Jul  7 15:44:08 xen SM: [28337] blktap2.activate
 Jul  7 15:44:08 xen SM: [28337] lock: acquired /var/lock/sm/ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0/vdi
 Jul  7 15:44:08 xen SM: [28337] Adding tag to: ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0
 Jul  7 15:44:08 xen SM: [28337] Activate lock succeeded
 Jul  7 15:44:08 xen SM: [28337] lock: opening lock file /var/lock/sm/319aebee-24f0-8232-0d9e-ad42a75d8154/sr
 Jul  7 15:44:08 xen SM: [28337] ['/usr/sbin/td-util', 'query', 'vhd', '-vpfb', '/var/run/sr-mount/319aebee-24f0-8232-0d9e-ad42a75d8154/ca88f8dc-4ab6-4be7-9084-1b41cbc8c1c0.vhd']
 Jul  7 15:44:08 xen SM: [28337]   pread SUCCESS

borzel

@borzel said in Testing ZFS with XCP-ng:

Jul 7 15:44:07 xen SM: [28311] result: {'o_direct_reason': 'SR_NOT_SUPPORTED',

Did find it after posting this and looking onto it... is this a known thing?

nraynaud

that's weird: https://github.com/xapi-project/sm/blob/master/drivers/blktap2.py#L1002

I don't even know how my tests did work before.

olivierlambert

Maybe because it wasn't triggered without a VDI live migration?

borzel

~~did no livemigration ...just local copy of a vm~~
... ah, I should read before I answer ...

borzel

~~@nraynaud Is there any info how to build blktap2 myself to test with my homelab?~~
I did find it here: https://xcp-ng.org/forum/topic/122/how-to-build-blktap-from-sources/3

borzel

I tested the updated version of blktap and build it like described in https://xcp-ng.org/forum/post/1677, but copying a vm within the SR fails

Async.VM.copy R:f286a572f8aa|xapi] Error in safe_clone_disks: Server_error(VDI_COPY_FAILED, [ End_of_file ])

borzel

the function safe_clone_disks is located in https://github.com/xapi-project/xen-api/blob/72a9a2d6826e9e39d30fab0d6420de6a0dcc0dc5/ocaml/xapi/xapi_vm_clone.ml#L139

it calls clone_single_vdi in https://github.com/xapi-project/xen-api/blob/72a9a2d6826e9e39d30fab0d6420de6a0dcc0dc5/ocaml/xapi/xapi_vm_clone.ml#L116

which calls Client.Async.VDI.copy from a XAPI-OCaml Module Client which I can not find

borzel

found something in /var/log/SMlog

Jul 21 19:52:40 xen SM: [17060] result: {'o_direct_reason': 'SR_NOT_SUPPORTED', 'params': '/dev/sm/backend
/4c8bc619-98bd-9342-85fe-1ea4782c0cf2/8e901c80-0ead-4764-b3d9-b04b4376e4c4',
'o_direct': True, 'xenstore_data': {'scsi/0x12/0x80': 'AIAAEjhlOTAxYzgwLTBlYWQtNDcgIA==', 'scsi/0x12/0x83': 
'AIMAMQIBAC1YRU5TUkMgIDhlOTAxYzgwLTBlYWQtNDc2NC1iM2Q5LWIwNGI0Mzc2ZTRjNCA=', 'vdi-uuid': 
'8e901c80-0ead-4764-b3d9-b04b4376e4c4', 'mem-pool': '4c8bc619-98bd-9342-85fe-1ea4782c0cf2'}}

Note the 'o_direct': True in this log entry. But I created the SR with other-config:o_direct=false

stormi

@borzel I'll let @nraynaud have a say, but first, to be sure, you built it with

xcp-build --build-local . --define 'xcp_ng_section extras'

and the resulting RPM contains .extras in its name?

borzel

yes, I did Checked it multiple times. Will check it again today to be 100% sure.

I also saw the right logoutput from @nraynaud new function where he probes the open with O_DIRECT and retries with O_DSYNC.

I have the "feel" that xapi or blktap copy's files in some situations without it's normal way. Maybe a special "file copy" without a open command?

Can I attach a debugger to blktap while in operration? This would also be needed for deep support of the whole server.

stormi

You can probably attach gdb to a running blktap, yes. Install the blktap-debuginfo package that was produced when you built blktap to make debug symbols available.

nraynaud

@borzel there is something fishy around here https://github.com/xapi-project/sm/blob/master/drivers/blktap2.py#L994 I am still unsure what to do.

I have not removed O_DIRECT everywhere in blktap, I was expecting to remove the remainder by the o_direct flag in python, but I guess I was wrong. we might patch the python.

borzel

Maybe we can create a new SR type "zfs" and copy the file SR implementation from https://github.com/xapi-project/sm/blob/master/drivers/FileSR.py
This would us later allow to create a more deeper integration of ZFS.

borzel

Success! I changed in /opt/xensource/sm/blktap2.py

 elif not ((self.target.vdi.sr.handles("nfs") or self.target.vdi.sr.handles("ext") or self.target.vdi.sr.handles("smb"))):

to

 elif not ((self.target.vdi.sr.handles("file")) or (self.target.vdi.sr.handles("nfs") or self.target.vdi.sr.handles("ext") or self.target.vdi.sr.handles("smb"))):

Than I deleted /opt/xensource/sm/blktap2.pyc and /opt/xensource/sm/blktap2.pyo so that the *.py file is used.

Now I can copy from other SR types to my ZFS SR.

But copy within my ZFS SR does not work...

borzel

some info about the o_direct flag: https://xenserver.org/blog/entry/read-caching.html

borzel

After reading some, I think we can not get it fully working in short time. Some of the tools might not work without o_direct support:

If the underlying file-system does not support O_DIRECT, utilities (e.g, vhd-util) may fail with error code 22 (EINVAL). Similarly, Xen may fail with a message as follows:
TapdiskException: ('create', '-avhd:/home/cklein/vms/vm-rubis-0/root.vhd') failed (5632 )

https://github.com/xapi-project/blktap/blob/master/README

Today there is just one fully working local ZFS configuration:

create your ZFS-Pool: zpool create ...
create a ZVOL (aka blockdevice): zfs create -V 50G pool/my_local_sr
create an EXT3 based SR: xe sr-create host-uuid=<UUID_of_your_host> type=ext shared=false name-label=<Name_of_my_SR> device-config:device=/dev/zvol/<pool-name>/<zvol-name>

It's not optimal, but working.