NFS が突然ハングアップしました。サービスを再起動することさえできません:
# /etc/init.d/nfs-kernel-server restart
* Stopping NFS kernel daemon [ OK ]
* Unexporting directories for NFS kernel daemon... [ OK ]
* Exporting directories for NFS kernel daemon... [ OK ]
* Starting NFS kernel daemon ^C
syslog によると、nfs は 120 秒以上ブロックされています。ログを理解するには？ここで何がうまくいかなかったのですか？
# cat /var/log/syslog | grep nfs
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248354] INFO: task nfsd:2318 blocked for more than 120 seconds.
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248363] nfsd D 0000000000000000 0 2318 2 0x00000000
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248406] [<ffffffffa02a28c0>] ? nfsd_proc_getattr+0xa0/0xa0 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248418] [<ffffffffa02a3c11>] nfsd_vfs_write.isra.13+0x81/0x3b0 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248422] [<ffffffffa02bf691>] ? lookup_clientid+0x51/0x80 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248426] [<ffffffffa02bf766>] ? nfsd4_lookup_stateid+0xa6/0xc0 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248429] [<ffffffffa02a7773>] nfsd_write+0x93/0x110 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248433] [<ffffffffa02b2281>] nfsd4_write+0x1b1/0x250 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248437] [<ffffffffa02b35ca>] nfsd4_proc_compound+0x56a/0x7c0 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248440] [<ffffffffa029fd2b>] nfsd_dispatch+0xbb/0x200 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248455] [<ffffffffa029f71f>] nfsd+0xbf/0x130 [nfsd]
Sep 4 10:02:11 InksedgeDev kernel: [2427120.248458] [<ffffffffa029f660>] ? nfsd_destroy+0x80/0x80 [nfsd]
Iostat の出力:
# iostat 5 5
Linux 3.13.0-29-generic (InksedgeDev) 09/04/2015 _x86_64_ (2 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
5.68 0.00 0.48 0.25 0.01 93.58
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
xvdap1 3.63 15.71 82.80 38138709 201066916
xvdb 0.01 0.05 0.01 119271 15231
xvdc 0.01 0.05 0.01 112329 14600
xvdf 4.25 155.14 175.05 376748353 425087092
md0 0.02 0.10 0.01 231288 29831
avg-cpu: %user %nice %system %iowait %steal %idle
0.30 0.00 0.20 49.75 0.00 49.75
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
xvdap1 0.00 0.00 0.00 0 0
xvdb 0.00 0.00 0.00 0 0
xvdc 0.00 0.00 0.00 0 0
xvdf 0.00 0.00 0.00 0 0
md0 0.00 0.00 0.00 0 0
何が原因でしょうか? トラブルシューティングの方法