Hi. I'd like to revisit a problem I put to the mailing list on the
27th July 2008.
My linux system hangs if I have a lengthy recovery of a raid-1
device going on at the same time as any significant network
traffic. If I terminate my networking applications the re-sync
succeeds; if I allow them to run then the re-sync will almost always
hang the system.
My PC is about 1.5 years old; it has a Gigabyte GA-P35-DS4 motherboard
with an Intel Core 2 Quad Q6600 CPU. The motherboard
has an Intel ICH9R northbridge with 6 SATA 2 ports and a 'Gigabyte'
(JMicron 20360/20363) southbridge with 2 SATA 2 ports. I have two
500GB Western Digital SATA 2 internal disks, both on the ICH9R northbridge,
as I used to get occasional SATA disconnects/errors if I had a disk under
heavy load on the JMicron controller. The two disks have 400GB
partitions in a MD raid1 mirror. I typically experience this problem when
I plug in a third disk (also on the ICH9R controller) to synchronise as
a backup procedure, but it also happens if I just have the two permanent
disks synchronising between themselves.
I'm running Linux 2.6.28.6. The motherboard has a Realtek RTL8111/8168B
gigabit ethernet controller which I have running in a 100Mbit full duplex
link to my ADSL modem. I'm using the kernel's standard r8169 driver for the
network.
If I have no significant network activity taking place (other than trivial
traffic from named, ntpd and the like) then my md1 recoveries always
succeed. But if I have a program maxing out the connection to my ISP -
about 160KB/sec down, 30KB/sec up - then the re-synchronisation will
always end up hanging:
o disk I/O stops - the disk activity LED will stop flashing, iostat statistics
will drop to zero, 'cat /proc/mdstat' will show dwindling I/O speeds and
ever-increasing finish times (from 200 minutes to 30,000+ minutes!).
o any access to the filesystem I have mounted on top of the md1 device
hangs.
o access to OTHER filesystems is fine, and anything independent of the
hung filesystem works as normal.
There are absolutely no errors reported by the system - nothing logged
to the console and nothing logged via syslog (the /var/log filesystem
is fully operational even while the recovering one is hung).
Looking at /proc/interrupts I can see that the 'eth0' driver has an
interrupt all to itself.
I haven't had a single SATA disconnect error since I moved all my disks
off the JMicron southbridge. I can 'dd' each drive simultaneously with
no errors and better than 70MB/sec throughput from each in parallel.
Does anyone know of any condition which would cause the md1
recovery process to silently hang like this? Can I get some sort of
debug/verbose log out of the raid software to work out why it's hanging?
Has anyone ever experienced this sort of problem - md recovery
'sensitivity' to network traffic? - on this motherboard?
Thanks,
Brad
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