RAID Driver needs non-destructive partition concatenation

From: Jeff V. Merkey (jmerkey@timpanogas.com)
Date: Thu Jan 20 2000 - 12:03:49 EST


Linux,

If the current RAID driver can support a mode that will concatenate
partitions together WITHOUT WRITING HEADER STUFF on the partition, we
can convert NetWare partitions to EXT2, and will put up free tools on
our site that do just that for Linux. Most NetWare partitions do not
use sectors 0-0xA0+4096 or the last cylinder on the partition, but there
are some configs where NetWare does use the last cylinder, depending on
NetWare version.

NTFS uses registry entries to concatenate together several IFS
partitions, and stores this in the system hive (registry database).
When we convert, we take the NetWare partitions in the system that have
stripes or host multiple volume segments on partitions, and group them
into an NTFS stripe set by concatenating all the partitions into one,
and then we write an MFT to disk with all the NTFS external attribute
lists (we have the real NTFS stuff here, not the Linux or BSD so we are
able to write our the log file, bit maps, etc correctly for NT). This
gets around the issues of having to move data around on the disk and
lets us fake out NT into thinking its on top of an NTFS stripe set
instead of a baunch of NetWare partitions with volume segments. When
sector 0 of the partition gets stamped with an NTFS boot record, the
volumes have been converted.

We are looking at doing this with NetWare-to-EXT2. If we take the
existing RAID driver, and change it to take a partition definition and
a list of partitions and merge them, are there any side effects that
anyone is aware of that would prevent EXT2 from working properly. We
could return the RAID driver to Pavel -- perhaps a better solution is
for Pavel to modify the RAID driver to support this mode so we could
provide a conversion tool like the one we ship on NT for Linux. I EXT2
on-disk formats the right direction -- should we look at EXT3 instead?

Please Advise,

Jeff

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