While I was using "cephfs" following error is observed -
------------------------------------------------------------------------------------------------
root@hemantsec-virtual-machine:~# cephfs /mnt/ceph/a --pool 3
invalid command
usage: cephfs path command [options]*
Commands:
show_layout -- view the layout information on a file or dir
set_layout -- set the layout on an empty file,
or the default layout on a directory
show_location -- view the location information on a file
Options:
Useful for setting layouts:
--stripe_unit, -u: set the size of each stripe
--stripe_count, -c: set the number of objects to stripe across
--object_size, -s: set the size of the objects to stripe across
--pool, -p: set the pool to use
Useful for getting location data:
--offset, -l: the offset to retrieve location data for
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It may be silly question but unable to figure it out.
:(
On Wed, Nov 21, 2012 at 8:59 PM, Sage Weil <sage@xxxxxxxxxxx> wrote:
> On Wed, 21 Nov 2012, hemant surale wrote:
>> > Oh I see. Generally speaking, the only way to guarantee separation is to
>> > put them in different pools and distribute the pools across different sets
>> > of OSDs.
>>
>> yeah that was correct approach but i found problem doing so from
>> abstract level i.e. when I put file inside mounted dir
>> "/home/hemant/cephfs " ( mounted using "mount.ceph" cmd ) . At that
>> time anyways ceph is going to use default pool data to store files (
>> here files were striped into different objects and then sent to
>> appropriate osd ) .
>> So how to tell ceph to use different pools in this case ?
>>
>> Goal : separate read and write operations , where read will be done
>> from one group of OSD and write is done to other group of OSD.
>
> First create the other pool,
>
> ceph osd pool create <name>
>
> and then adjust the CRUSH rule to distributed to a different set of OSDs
> for that pool.
>
> To allow cephfs use it,
>
> ceph mds add_data_pool <poolid>
>
> and then:
>
> cephfs /mnt/ceph/foo --pool <poolid>
>
> will set the policy on the directory such that new files beneath that
> point will be stored in a different pool.
>
> Hope that helps!
> sage
>
>
>>
>>
>>
>>
>> -
>> Hemant Surale.
>>
>>
>> On Wed, Nov 21, 2012 at 12:33 PM, Sage Weil <sage@xxxxxxxxxxx> wrote:
>> > On Wed, 21 Nov 2012, hemant surale wrote:
>> >> Its a little confusing question I believe .
>> >>
>> >> Actually there are two files X & Y. When I am reading X from its
>> >> primary .I want to make sure simultaneous writing of Y should go to
>> >> any other OSD except primary OSD for X (from where my current read is
>> >> getting served ) .
>> >
>> > Oh I see. Generally speaking, the only way to guarantee separation is to
>> > put them in different pools and distribute the pools across different sets
>> > of OSDs. Otherwise, it's all (pseudo)random and you never know. Usually,
>> > they will be different, particularly as the cluster size increases, but
>> > sometimes they will be the same.
>> >
>> > sage
>> >
>> >
>> >>
>> >>
>> >> -
>> >> Hemant Sural.e
>> >>
>> >> On Wed, Nov 21, 2012 at 11:50 AM, Sage Weil <sage@xxxxxxxxxxx> wrote:
>> >> > On Wed, 21 Nov 2012, hemant surale wrote:
>> >> >> >> and one more thing how can it be possible to read from one osd and
>> >> >> >> then simultaneous write to direct on other osd with less/no traffic?
>> >> >> >
>> >> >> > I'm not sure I understand the question...
>> >> >>
>> >> >> Scenario :
>> >> >> I have written file X.txt on some osd which is primary for filr
>> >> >> X.txt ( direct write operation using rados cmd) .
>> >> >> Now while read on file X.txt is in progress, Can I make sure
>> >> >> the simultaneous write request must be directed to other osd using
>> >> >> crushmaps/other way?
>> >> >
>> >> > Nope. The object location is based on the name. Reads and writes go to
>> >> > the same location so that a single OSD can serialize request. That means,
>> >> > for example, that a read that follows a write returns the just-written
>> >> > data.
>> >> >
>> >> > sage
>> >> >
>> >> >
>> >> >> Goal of task :
>> >> >> Trying to avoid read - write clashes as much as possible to
>> >> >> achieve faster operations (I/O) . Although CRUSH selects osd for data
>> >> >> placement based on pseudo random function. is it possible ?
>> >> >>
>> >> >>
>> >> >>
>> >> >> -
>> >> >> Hemant Surale.
>> >> >>
>> >> >>
>> >> >>
>> >> >> On Tue, Nov 20, 2012 at 10:15 PM, Sage Weil <sage@xxxxxxxxxxx> wrote:
>> >> >> > On Tue, 20 Nov 2012, hemant surale wrote:
>> >> >> >> Hi Community,
>> >> >> >> I have question about port number used by ceph-osd daemon . I
>> >> >> >> observed traffic (inter -osd communication while data ingest happened)
>> >> >> >> on port 6802 and then after some time when I ingested second file
>> >> >> >> after some delay port no 6804 was used . Is there any specific reason
>> >> >> >> to change port no here?
>> >> >> >
>> >> >> > The ports are dynamic. Daemons bind to a random (6800-6900) port on
>> >> >> > startup and communicate on that. They discover each other via the
>> >> >> > addresses published in the osdmap when the daemon starts.
>> >> >> >
>> >> >> >> and one more thing how can it be possible to read from one osd and
>> >> >> >> then simultaneous write to direct on other osd with less/no traffic?
>> >> >> >
>> >> >> > I'm not sure I understand the question...
>> >> >> >
>> >> >> > sage
>> >> >> --
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>> >> >>
>> >> >>
>> >>
>> >>
>>
>>
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