[Users] Cloud Storage for OpenVZ Containers

[Kirill Korotaev]

Edward,

can you send me in private email output of:
# pstorage -c <cluster> stat
output?

Do you have a skype?

Thanks,
Kirill



On 29 Jan 2014, at 10:26, Edward Konetzko <konetzed at gmail.com<mailto:konetzed at gmail.com>> wrote:

On 01/28/2014 09:51 AM, Kir Kolyshkin wrote:
On 28 January 2014 02:55, Kirill Korotaev <dev at parallels.com<mailto:dev at parallels.com>> wrote:
>> On 25 Jan 2014, at 07:38, Rene C. openvz at dokbua.com<mailto:openvz at dokbua.com> wrote:
>>
>
> Hi,
>
> I read the website about the cloud storage and I found some words, which seems familiar for me.
>
> May I ask, which filesystem do you use to be able to regularly scrub and self-heal the filesystem?
>
> Personaly I use zfsonlinux in production for a long time now and I am very satisfied with it, and based on your description, it seems you should use something like that and something on top of the native filesystem to get a cloud storage.
>
> Or you use a ceph or alike "filesystem", which has similar capabilities with cloud features.

It’s more like a ceph. Data is stored in a distributed way, so unlike to zfs you have access to the data even in case of node failure (crash, CPU/memory fault etc.) and access is available from ANY cluster node.
As such we store the data and maintain checksums on every node and can do periodic scrubbing of the data.

Just to clarify -- this is Parallels own distributed/cloud filesystem, not CEPH or GlusterFS,
but similar to. For more info, check the links at https://openvz.org/Parallels_Cloud_Storage#External_links




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Setup a cluster using Centos 6.5 64bit, fresh install in KVM instances.  I wanted to test functionality not actual speed.

All software was latest as of last night and I followed the quick how to here https://openvz.org/Parallels_Cloud_Storage

Everything works great until I try to create an instance using the command "vzctl create 101 --layout ploop --ostemplate centos-6-x86_64 --private /pcs/containers/101" from the docs.

About one mb of data is written to disk and then it just hangs.  The following is output from dmesg

[  360.414242] INFO: task vzctl:1646 blocked for more than 120 seconds.
[  360.414770] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  360.415406] vzctl         D ffff88007e444500     0  1646   1611    0 0x00000084
[  360.415418]  ffff88007ea59a68 0000000000000086 ffff8800ffffffff 000006b62934b8c0
[  360.415428]  0000000000000000 ffff88007e9f2ad0 0000000000005eaa ffffffffad17694d
[  360.415437]  000000000ad7ef74 ffffffff81a97b40 ffff88007e444ac8 000000000001eb80
[  360.415452] Call Trace:
[  360.415492]  [<ffffffff81517353>] io_schedule+0x73/0xc0
[  360.415516]  [<ffffffff811f39b3>] wait_on_sync_kiocb+0x53/0x80
[  360.415537]  [<ffffffffa04dbf47>] fuse_direct_IO+0x167/0x230 [fuse]
[  360.415558]  [<ffffffff8112e948>] mapping_direct_IO+0x48/0x70
[  360.415567]  [<ffffffff811301a6>] generic_file_direct_write_iter+0xf6/0x170
[  360.415576]  [<ffffffff81130c8e>] __generic_file_write_iter+0x32e/0x420
[  360.415585]  [<ffffffff81130e05>] __generic_file_aio_write+0x85/0xa0
[  360.415594]  [<ffffffff81130ea8>] generic_file_aio_write+0x88/0x100
[  360.415605]  [<ffffffffa04da085>] fuse_file_aio_write+0x185/0x430 [fuse]
[  360.415623]  [<ffffffff811a530a>] do_sync_write+0xfa/0x140
[  360.415641]  [<ffffffff8109d930>] ? autoremove_wake_function+0x0/0x40
[  360.415655]  [<ffffffff812902da>] ? strncpy_from_user+0x4a/0x90
[  360.415664]  [<ffffffff811a55e8>] vfs_write+0xb8/0x1a0
[  360.415671]  [<ffffffff811a5ee1>] sys_write+0x51/0x90
[  360.415681]  [<ffffffff8100b102>] system_call_fastpath+0x16/0x1b

Even just trying to create a 10k file with dd causes a task to hang.  "dd if=/dev/zero of=/pcs/test.junk bs=1k count=10"


Any ideas? Anymore info you would like for debugging.
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