The new models seem to be database centric. For example, Blackcomb
purports to use the JET replacement engine and will talk directly to the
disk. FAT and NTFS will be APIs into the database.
This method of allocating and managing disks will have some dramatic
impact on how SAN and NAS architectures are implemented.
I am still waiting to see how it all pans out.
Jamey
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Geoff Clow
Sent: Friday, February 22, 2002 2:12 PM
To: File Systems Developers
Subject: [ntfsd] Re: How to share storage device on logical block acce
ss level?
I suppose the statement “no commercial cluster FS for NT” means that the
cluster file systems available for Windows do not support concurrent
Write access to the same file between servers. Is that correct, or did
you have another distinction in mind?
Shared Read / Exclusive Write SAN-based shared device file systems are
cluster file systems, and there appear to be such products for Windows.
They are used in Read-intensive applications, such as large numbers of
computers all serving-up the same video content residing on shared
storage.
ADIC provides the CentraVision monolithic file system (CVFS) developed
by Mountaingate for heterogeneous hosts:
http://www.adic.com/ibeCCtpSctDspRte.jsp?minisite=10000
http:ction=10121> &respid=22372§ion=10121
IBM provides the SANergy layered file system developed by Mercury, as a
redirector filter I believe:
http://www.tivoli.com/products/index/sanergy/
Veritas provides a similar product:
http://www.veritas.com/products/listing/ProductBenefitList.jhtml?product
Id=sanpointdirect
For non-Windows platforms, Jamey mentioned GFS from Sistina:
http://www.sistina.com/products_gfs.htm
-----Original Message-----
From: xxxxx@veritas.com [mailto:xxxxx
mailto:xxxxx@veritas.com]
Sent: Friday, February 22, 2002 8:17 AM
To: File Systems Developers
Subject: [ntfsd] Re: How to share storage device on logical block access
level?
I worked on “Digital Clusters for Windows NT” several years ago, and we
determined that there was no simple answer. Thus we developed the
“sequential sharing” model for shared SCSI disk usage, which MSCS still
uses today. At any given time, only one node is allowed to access a
shared
disk.
Many other people have replied, but only Andy Champ has given you a clue
about the answer. The answer is - you can’t do it without a true
cluster
filesystem, running on all computers sharing the disk, and communicating
with each other. Other operating systems have achieved this in the past
(the classic is DEC’s VMS Clusters, released in 1984). But as of today,
no
commercial cluster filesytem has been released for NT.
You could not get the right results with a simple filter driver, and
might
even have troubles with a full filesytstem driver too, since the NT
cache
manager is also involved in writing to disk.
Good luck!
Carl Appellof
VERITAS Software Global Corporation
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