topic Re: Document on read/write on 2 servers in Disk Enclosures

Document on read/write on 2 servers

Jason Ng Teng Po — Tue, 29 Dec 2009 01:44:34 GMT

Hi All,

Do you guys know which document I can find that stated that 1 vdisk cannot read/write at the same time on 2 servers?

Thanks in advance.

Re: Document on read/write on 2 servers

Patrick Terlisten — Tue, 29 Dec 2009 07:21:36 GMT

Hello,

this is by design for the most filesystems. Only cluster filesystems can handle this. There is a lock manager, which manages the multiple access to the same file from more then one host.

Best regards,
Patrick

Re: Document on read/write on 2 servers

Jason Ng Teng Po — Tue, 29 Dec 2009 07:29:42 GMT

Hi Patrick thanks your feedback. I myself as a technical person knows about this but my customer requires a written proof from HP document about this. I tried searching around for this in HP website unfortunately I cannot find any :(

Re: Document on read/write on 2 servers

Patrick Terlisten — Tue, 29 Dec 2009 07:48:44 GMT

Hello,

I don't think that there is a document from HP. Maybe you will find something written by the operating system developer, if you're using windows the Microsoft TechNet would be advisable.

Best regards,
Patrick

Re: Document on read/write on 2 servers

Víctor Cespón — Tue, 29 Dec 2009 09:09:13 GMT

If you're talking about an storage array, it's a block server, not a file server.
Your customer is confusing things. There's other devices like NAS that can act as file servers, and share files for several servers.

A block server provides a series of empty data sectors, and then the operating system creates it's filesystem structures on it (FAT32 / NTFS / Extfs2 / LVM / etc). The OS keeps tables to know what data sectors belong to what files. These tables have to be updated by the OS in a consistent way.
If two independent operating systems use the same physical space, each one will create it's mapping between files and data sectors, and there will be a mix of both filesystems on the disk.