Docadmin at 21:00, 22 January 2010

2010-01-22T21:00:04Z

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	'''''Note:''''' The content on this page reflects the state of design of a Lustre feature at a particular point in time and may contain outdated information.		'''''Note:''''' ''The content on this page reflects the state of design of a Lustre feature at a particular point in time and may contain outdated information.''

	== Use Cases to cover ==		== Use Cases to cover ==

Docadmin: Protected "Architecture - Client Cleanup" ([edit=sysop] (indefinite) [move=sysop] (indefinite))

2010-01-21T19:13:05Z

Protected "Architecture - Client Cleanup" ([edit=sysop] (indefinite) [move=sysop] (indefinite))

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Docadmin at 23:54, 18 January 2010

2010-01-18T23:54:34Z

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			'''''Note:''''' The content on this page reflects the state of design of a Lustre feature at a particular point in time and may contain outdated information.

	== Use Cases to cover ==		== Use Cases to cover ==

Docadmin: /* Implementation Constraints */

2010-01-18T23:36:05Z

Implementation Constraints

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	# Re-use as much existing code as possible		# Re-use as much existing code as possible
	# Quality		# Quality

	~~[[Category:QAS\|Client Cleanup]]~~

Docadmin: moved QAS Client Cleanup to Architecture - Client Cleanup

2010-01-15T18:53:09Z

moved QAS Client Cleanup to Architecture - Client Cleanup

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Docadmin: 1 revision

2010-01-15T18:51:39Z

1 revision

← Older revision	Revision as of 11:51, 15 January 2010
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Nikita: Update business drivers

2007-08-08T17:51:46Z

Update business drivers

New page

== Use Cases to cover ==

{|cellspacing="0" border="1"
!Description
!Semantics
|-
|dlm:acquiring lock||actions performed on each layer. Interaction with dlm in the bottom layer.
|-
|dlm:releasing lock||actions on every layer.
|-
|dlm:maintaining lock lru size||where decision to cancel locks is taken.
|-
|dlm:blocking ast||notification of layers
|-
|dlm:cancellation ast||actions done at every layer
|-
|dlm:glimpse ast||actions done at every layer
|-
|dlm:lock conversion||client should be able to convert read lock to write lock without flushing out pages
|-
|io:read-ahead||have to be encapsulated into llite layer. Current semantics is to be preserved.
|-
|io:kms||current semantics is to be preserved. Kms handing should be encapsulated into llite.
|-
|io:read||how layers handle typical read call, including read-ahead.
|-
|io:short read||how short read is handled.
|-
|io:write||how layers handle typical write call.
|-
|io:O_APPEND||write into file descriptor opened with O_APPEND
|-
|io:O_SYNC||write into file descriptor opened with O_SYNC
|-
|io:O_DIRECT||write into file descriptor opened with O_DIRECT
|-
|io:no-lsm||write(2) into object that doesn't yet have objects allocated on ost.
|-
|io:lockless||how lockless io fits into model.
|-
|io:intents||check that ost intents can be implemented.
|-
|io:truncate||how typical truncate case is handled. Paths through vfs, locking. Non-page aligned case.
|-
|io:unlink||ost-related part of unlink(2) handling.
|-
|io:getattr||parallel rpcs.
|-
|io:mixed page size||bug 686.
|-
|io:recoverable-errors||bug 11710
|-
|io:rpc formation||how/when it is decided that rpc is ready to be sent.
|-
|io:epoch closure||size on mds.
|-
|io:flock||POSIX locking.
|-
|io:abortions due to recovery||(ask Peter for details)
|-
|io:attributes||how attribute passing during read and write is handled.
|-
|io:migration||interaction between stripe sub-object migration and io.
|-
|io:parallel io||running out of cache space for certain osc/oss should not block read/write streaming data to other servers
|-
|io:extremely wide striping||scalability of system with large number of oss
|-
|io:updates of file layout||client has to keep track of file layout accuracy to accommodate for migration
|-
|sns:read-modify-write||how read-modify-write is done (especially, locking).
|-
|sns:reconstruct-write||where `old' page is kept.
|-
|sns:asynchronous mirroring||how raid1 io is done in parallel.
|-
|sns:raidframe compliance||check that sns fits into raidframe model.
|-
|sns:caching parity||how parity pages are cached (vm issues).
|-
|p2p:read||read call, fetching data from other client.
|-
|p2p:read-failure||handle other client failure, fall back to server seed.
|-
|p2p:fetch||other client fetches data from this one.
|-
|vm:mmap-fault||page fault handling.
|-
|vm:mmap-dirty||grants vs. mmap.
|-
|vm:mmap-locking||locking for read/write-with-mmapped-buffer case.
|-
|vm:grants||how out-of-grant situation is handled. When grant is renewed. How multiple mount points on the same node are handled.
|-
|vm:memory pressure||how low memory conditions are handled.
|-
|vm:balance_dirty_pages()||response to ->writepages().
|-
|vm:pdflush||cleaning old data.
|-
|vm:no-cache mode||keep liblustre in mind.
|-
|misc:lov-osc on mds||changes on the server side.
|-
|misc:local mounts||optimizations for server mounts.
|-
|misc:stacking||check that configurations without lov or osc are possible.
|-
|misc:join file||data structures for join file.
|}

== Business Drivers ==

# reduce bugs
# SNS
# peer-to-peer traffic of client data caches
# full parallelism
# concurrent I/O to one file
# lock conversion
# extremely wide striping
# updates of file layouts

== Models to consider ==

{| border=0
| current situation
|-
| OSC as a block device
|-
| OSC owns pages
|}

== Implementation Constraints ==

# Re-use as much existing code as possible
# Quality

[[Category:QAS|Client Cleanup]]