I've noticed that a disk in RAID5 has been disabled due to the I/O error..

scsi7: ERROR on channel 0, id 0, lun 0, CDB: Read (10) 00 02 ab 2d 3f 00 00 f8 00
Current sd08:71: sense key Medium Error
Additional sense indicates Unrecovered read error
 I/O error: dev 08:71, sector 44772608
raid5: Disk failure on sdh1, disabling device. Operation continuing on 7 devices
md: recovery thread got woken up ...
md: updating md5 RAID superblock on device
md: (skipping faulty sdh1 )
md: sdg1 [events: 00000004]<6>(write) sdg1's sb offset: 244195904
md5: no spare disk to reconstruct array! -- continuing in degraded mode
md: recovery thread finished ...
md: sdf1 [events: 00000004]<6>(write) sdf1's sb offset: 244195904
md: sde1 [events: 00000004]<6>(write) sde1's sb offset: 244195904
md: sdd1 [events: 00000004]<6>(write) sdd1's sb offset: 244195904
md: sdc1 [events: 00000004]<6>(write) sdc1's sb offset: 244195904
md: sdb1 [events: 00000004]<6>(write) sdb1's sb offset: 244195904
md: sda1 [events: 00000004]<6>(write) sda1's sb offset: 244195904

Hmm, we (FSIJ) need to prepare new disks for snapshot.debian.net, not only it will be short on disk space (1.4T used, 177G avail 89% used) but also it has no more spare disks on RAID5...