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"
<[EMAIL PROTECTED]>
To: "Yuri Kirsanov" <[EMAIL PROTECTED]>
Cc: <[email protected]>
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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