[Ocfs2-users] OCFS2 strage freezes
Yuri Kirsanov
flash at preferance.ru
Tue Mar 4 11:09:18 PST 2008
Thank you very much for your help!
I believe ocfs2 will be very good for my purposes.
----- Original Message -----
From: "Sunil Mushran" <Sunil.Mushran at oracle.com>
To: "Yuri Kirsanov" <flash at preferance.ru>
Cc: <ocfs2-users at oss.oracle.com>
Sent: Tuesday, March 04, 2008 9:50 PM
Subject: Re: [Ocfs2-users] OCFS2 strage freezes
> No delay in read as we won't have to flush those pages to disk.
>
> Yuri Kirsanov wrote:
>> Yes, now I see it, thank you very much. So, it happends only when a
>> large amount of data has to be flushed to disk on target system, right?
>>
>> Then, if I already have big file and just reading it from server,
>> there will be no delays in access from two nodes, right?
>>
>> ----- Original Message ----- From: "Sunil Mushran"
>> <Sunil.Mushran at oracle.com>
>> To: "Yuri Kirsanov" <flash at preferance.ru>
>> Cc: <ocfs2-users at oss.oracle.com>
>> Sent: Tuesday, March 04, 2008 9:28 PM
>> Subject: Re: [Ocfs2-users] OCFS2 strage freezes
>>
>>
>>> stat-ing a file makes the fs acquire a readlock (PR) forcing the
>>> other node
>>> to downgrade from writelock (EX) which then forces it to flush the
>>> dirty pages
>>> to disk. Say you have 500M to flush and your iscsi setup's io thruput
>>> is 30MB/s.
>>> That'll be 16 secs.
>>>
>>> Note: The nodes are not frozen. The ls and cp processes are waiting
>>> on the
>>> pages to flush to disk.
>>>
>>> You can confirm this by repeating the test and doing a "find ."
>>> instead of ls.
>>> The former will not stat the file (will only stat the directory) and
>>> thus avoid
>>> the force flush seen above.
>>>
>>> Yuri Kirsanov wrote:
>>>> Good day, everyone.
>>>>
>>>> I have SAN server build with Openfiler OS, with iSCSI mode turned
>>>> on. I have two nodes, which connect to that server via iSCSI, using
>>>> one of two active iSCSI partitions. I've installed ocfs2 1.3.3 with
>>>> kernel 2.6.23.1, configured it, made ocfs2 partition and was
>>>> successful in mounting it on both nodes. Everything works just fine,
>>>> I can upload file from one node and delete it using another one,
>>>> except for one strange thing. When I'm using ocfs2 mounted partition
>>>> from one node, for example, uploading 1Gb test file into it, and I
>>>> try to access that partition from another node - just to read
>>>> directory, for example, - both nodes "freeze" for about 15-20
>>>> seconds, both operations just stops for a while, and then copying
>>>> continues on first node, while second one gets directory listing.
>>>>
>>>> I have no errors on both nodes, neither iSCSI ones, no ocfs2. All
>>>> three servers are joined together using 1Gbit/sec network switch and
>>>> there's no other machines on that switch.
>>>>
>>>> If you need any information, please feel free to ask me about it.
>>>> Thanks in advance!
>>>>
>>>> _______________________________________________
>>>> Ocfs2-users mailing list
>>>> Ocfs2-users at oss.oracle.com
>>>> http://oss.oracle.com/mailman/listinfo/ocfs2-users
>>>>
>>>
>>>
>>
>
>
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