[sam-qfs-discuss] sparc MDS / x86 MDS

[Tom Albers]

Hi Lisa,

The answer is 'yes' - assume by 2 MDS's you mean the following:

SPARC MDS existing filesystem with x4600 client
x4600 MDS new filesystem with SPARC client

We support mixed architectures in a shared QFS configuration, but
require EFI labels on the disks for this to work.  All potential
metadata servers (for the purpose of failover) need to be of the
same architecture.  By potential metadata servers, I mean those
that have a numeric value in the server priority field of the
shared QFS hosts file (man hosts.fs).

Here are some other notes from the 4.4 release notes.

Tom

----------------

The question is "How to you switch QFS metadata server architectures?"
from SPARC to x64 or from x64 to SPARC.

Here are the main points extracted from the SAM-QFS 4.4 release notes.

You cannot change the architecture type of the server responsible for
control of the file system metadata operations (i.e. the server that was
used to create the file system with the sammkfs(1M) command) by simply
moving the disks from one server to the other. For a Sun StorEdge QFS
standalone file system, this means that you cannot mount the file system on
a server that has a different architecture type from the one that created
it. For a Sun StorEdge QFS shared file system, this means that you cannot
change the architecture type of the metadata server or any potential
metadata servers. This is because the different architectures use different
byte-ordering schemes (endianness). However, you can migrate data from one
architecture type to the other by copying the file system to temporary
storage using either qfsdump(1M) or samfsdump(1M), re-creating the file
system using sammkfs(1M), and then repopulating the file system with
qfsrestore(1M) or samfsrestore(1M).

EFI labels are required on all shared disks if your Sun StorEdge QFS shared
file system configuration contains both the Solaris 10 OS on x64 platforms
and the Solaris 9 or Solaris 10 OS on SPARC platforms.

Use the Solaris prtvtoc(1M) command to determine whether a disk contains
SMI or EFI labels. Under the Dimensions section of the output, SMI labels
list the number of accessible cylinders, whereas EFI labels list the number
of accessible sectors.

To convert disk labels from the default SMI VTOC8 to EFI, copy the file
system to temporary storage using qfsdump(1M) or samfsdump(1M), relabel the
disks with EFI labels using the Solaris format -e command, re-create the
file system using sammkfs(1M), and repopulate the file system with
qfsrestore(1M) or samfsrestore(1M).

When using the Solaris format -e command to create EFI labels, you can
select the partition command from the menu to create and modify partitions
(slices). When doing this, you must specify a tag id name of usr, rather
than stand or unassigned, for EFI labels.

Note that EFI labels reserve the first 34 sectors, which misaligns Sun
RAID-5 storage from a performance perspective. Unless you realign the
storage, you will incur a RAID-5 read/modify/write performance penalty when
writing. You can avoid this performance penalty by selecting the proper
starting sector for all disk partitions for your particular storage
configuration. For example, an 8+P Sun StorEdge T3 array with a 64K block
size should have starting sectors that are multiples of 1024 for all disk
slices ((8 * 64 * 1024) / 512 = 1024). Similarly, a 5+P Sun StorEdge FC
3510 array with a 128K block size should have starting sectors that are
multiples of 1280 for all disk slices ((5 * 128 * 1024) / 512 = 1280).

----------------

Smith, Lisa wrote:
> we are getting ready to replace our sparc MDS server with an x86 x4600
> server.  
> 
> can i create a shared qfs filesystem on the x86 MDS and make the sparc
> MDS a shared client of the x86.  2 MDS's???  i could move the existing
> data from the old MDS to the new MDS a little quicker that way!!!
> 
> 
> 
> thanks again,
> lisa
> 
> repeat info:  we have shared samfs/qfs 4.6.25, currently we have all
> sparc systems (MDS server sol9 & shared clients) and will soon (month or
> so) move from the sparc MDS to an x86 MDS (x4600 sol10) with the same
> sparc clients and one day (several months) we will add linux (RH4&5)
> shared qfs clients.
> 
> Lisa W. Smith
> Naval Oceanographic Office
> Stennis Space Center MS 39522
> _______________________________________________
> sam-qfs-discuss mailing list
> sam-qfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/sam-qfs-discuss

-- 

Thanks,
Tom