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I am trying to copy a file from /backup/ folder to /backup/abc/ and it is taking a lot of time. The copy operation on performed on other server is pretty fast.

# df -HP
Filesystem      Size  Used Avail Use% Mounted on
/dev/sdc3       482G  351G  107G  77% /
tmpfs           4.2G   74k  4.2G   1% /dev/shm
/dev/sdc1       204M   36M  157M  19% /boot
/dev/sdb3       2.0T  590G  1.3T  32% /data
/dev/sda4       2.0T  705G  1.2T  38% /backup

The write speed of the disks is extremely slow compared to other servers those I have. What can be the reason behind this?

# hdparm -t /dev/sdc3
/dev/sdc3:
 Timing buffered disk reads:   2 MB in  3.00 seconds = 682.67 kB/sec

# hdparm -t /dev/sdc1
/dev/sdc1:
 Timing buffered disk reads:   2 MB in  4.10 seconds = 499.51 kB/sec

# hdparm -t /dev/sdb3
/dev/sdb3:
 Timing buffered disk reads: read(2097152) returned 4096 bytes

# hdparm -t /dev/sda4
/dev/sda4:
 Timing buffered disk reads:   4 MB in  6.10 seconds = 671.48 kB/sec

Update: More info

# fdisk -l

Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x3b011cfb

   Device Boot      Start         End      Blocks   Id  System
/dev/sda4               1      243201  1953512001   83  Linux
Partition 4 does not start on physical sector boundary.

Disk /dev/sdc: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0000272a

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sdc2              26        1301    10240000   82  Linux swap / Solaris
/dev/sdc3            1301       60802   477940736   83  Linux
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  • What does syslog show? Any error messages regarding disks? Jul 29, 2014 at 5:21
  • The disk named /data (/dev/sdb3) is corrupt. But does it affect the performance of the other /backup disk?
    – shantanuo
    Jul 29, 2014 at 5:48
  • Could you use fdisk -l -u=sectors? Just to check the proper alignment of the partitions (at least for sda). Could you also copy a big file from sdc3 to sda4 (or vice versa)? Use the command as root sync; echo 3 > /proc/sys/vm/drop_caches; time cp /tmp/bigfile /backup/ (replace /tmp/bigfile by any big file on your sdc3 partition, a file bigger than 100 MB would be good). Report us the file size and the time to copy it as reported by the time command.
    – Huygens
    Jul 29, 2014 at 9:23
  • @shantanuo could you provide the information requested in my previous comment?
    – Huygens
    Aug 5, 2014 at 8:45
  • I do not have access to that server now. But the only question that I have is - can disabling write cache affect the server performance like this?
    – shantanuo
    Aug 6, 2014 at 10:09

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