[Ocfs2-users] OCFS2 strage freezes

[Yuri Kirsanov]

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!
>>
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>
>