Software RAID/Filesystem problems?

kwijibo@zianet.com
Tue, 28 May 2002 12:34:46 -0600


Hello,

I have run into a problem with software raid with large filesystems.
I am not sure if this is a software raid limitation or a filesystem
limitation. I currently have two 3ware raid controllers that have
1.1TB (yes, terrabyte) of space on each. I want to stripe the two
hardware raid controllers using software raid but when I try to make
the raid using the command mkraid /dev/md0 it pukes out this:

DESTROYING the contents of /dev/md0 in 5 seconds, Ctrl-C if unsure!
handling MD device /dev/md0
analyzing super-block
disk 0: /dev/sdb1, 1120597978kB, raid superblock at 1120597888kB
disk 1: /dev/sdc1, 1120597978kB, raid superblock at 1120597888kB
raid0: looking at sdb1
raid0: comparing sdb1(1120597888) with sdb1(1120597888)
raid0: END
raid0: ==> UNIQUE
raid0: 1 zones
raid0: looking at sdc1
raid0: comparing sdc1(1120597888) with sdb1(1120597888)
raid0: EQUAL
raid0: FINAL 1 zones
raid0: zone 0
raid0: checking sdb1 ... contained as device 0
(1120597888) is smallest!.
raid0: checking sdc1 ... contained as device 1
raid0: zone->nb_dev: 2, size: -2053771520
raid0: current zone offset: 1120597888
raid0: done.
raid0 : md_size is -2053771520 blocks.
raid0 : conf->smallest->size is -2053771520 blocks.
raid0 : nb_zone is 1.
raid0 : Allocating 8 bytes for hash.

Notice the huge negative numbers -2053771520. I have tried this with
a couple different block sizes but it doesn't help. When I build a
filesystem
on it, in this case I am trying reiserfs, it builds it but in the
message log I
have these errors:

09:00: rw=0, want=134217729, limit=-2053771520
attempt to access beyond end of device
09:00: rw=0, want=134217730, limit=-2053771520
attempt to access beyond end of device
09:00: rw=0, want=134217731, limit=-2053771520
attempt to access beyond end of device

There are quite a few, I didn't post them all. Then when I mount the fs
it only reports it as about a 93GB filesystem instead of the 2.2TB it should
be. I did this same configuration in RAID 1(mirror) and it all worked
well, no
errors and the reported filesystem size was correct. So I guess my question
is: Am I hitting a kernel limit here or a filesystem limit, or is this
just a plain
ol bug? What is the current maximum filesystem size? I need to I can try
ext3 but it always takes a bit to format. This is on RedHat 7.3 with the
stock 2.4.18-4smp kernel. I also tried it with the standard 2.4.18
kernel with
the same results. Any suggestions/information would be appreciated. Let
me know if any more info would help, I usually forget info that is
important.

Here is a copy of my /etc/raidtab (currently set up for mirroring, not
stripping)

raiddev /dev/md0
raid-level 1
nr-raid-disks 2
persistent-superblock 1
chunk-size 4
device /dev/sdb1
raid-disk 0
device /dev/sdc1
raid-disk 1

Thanks,
Steven

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