2009/01/18
My email to Western Digital:
I have a Linux box which I use for MythTV, SqueezeCenter, as a file server etc. The primary drive is a WD5000AAKS and performs quite well, so I use a large partition on it for the MythTV recordings. Later I added this WD1000FYPS for longer-term file storage, and I've always been dissatisfied with the performance. It's strange, because hdparm reports good results:
[neutron][01:34:48 PM] hdparm -tT /dev/sda
/dev/sda: Timing cached reads: 1974 MB in 2.00 seconds = 986.64 MB/sec Timing buffered disk reads: 198 MB in 3.01 seconds = 65.70 MB/sec
[neutron][01:49:00 PM] hdparm -tT /dev/sdb
/dev/sdb: Timing cached reads: 2160 MB in 2.00 seconds = 1080.53 MB/sec Timing buffered disk reads: 224 MB in 3.02 seconds = 74.22 MB/sec
(it should be even faster than the 500 gig drive) but it seems like in normal usage, the seek time is really bad or something. The drive can go for several minutes at a time making rhythmic seek noises, much louder than the other one. While it is doing this, any files stored on that drive are not very accessible - even doing "ls" can take a very long time, as much as half a minute or so. I have not had any data loss though. I don't know what to blame the performance on, but I would bet that if I get a different model of terabyte drive and transfer everything to it, I will see a huge difference in performance. I just wondered if there are some known problems along these lines - something caused by the RAID optimization, or the "green" aspects or something that can be corrected with a firmware update, or maybe it's an actual defect (since I'm reading a lot of reviews about problems with this one, people losing all their data after a day, or a month). If I can still trust this drive not to lose data, maybe I just have to put it in a box and use it for an external backup drive, because it can transfer data reasonably fast as long as there's not too much seeking involved.
Then I tried Bonnie++... now it's very obvious there is a performance difference! On sdb it was crunching for many minutes, on sda for much less time. I guess it's telling me this drive has problems with file creation, but not sure how I can narrow down the problem further.
/dev/hda:
Version 1.93c ------Sequential Output------ --Sequential Input- --Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
neutron 6G 274 98 51301 18 26301 7 1463 96 59167 9 231.7 3
Latency 57729us 4414ms 1220ms 51215us 214ms 282ms
Version 1.93c ------Sequential Create------ --------Random Create--------
neutron -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 15594 74 +++++ +++ 18589 98 18627 87 +++++ +++ 16965 95
Latency 17607us 10673us 3077us 38672us 755us 14265us
/dev/hdb:
Version 1.93c ------Sequential Output------ --Sequential Input- --Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
neutron 6G 237 98 36724 17 20134 5 1391 98 63035 10 30.4 1
Latency 51377us 5875ms 3985ms 27709us 1970ms 3581ms
Version 1.93c ------Sequential Create------ --------Random Create--------
neutron -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 45 1 +++++ +++ 13180 72 5579 77 +++++ +++ 12702 73
Latency 293s 313us 212ms 12460us 12142us 11643us
Both drives are formatted with ReiserFS.
[neutron][02:33:27 PM] fdisk -l /dev/sda Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x8e9c8e9c Device Boot Start End Blocks Id System /dev/sda1 * 1 7296 58605088+ 7 HPFS/NTFS /dev/sda2 7297 7298 16065 83 Linux /dev/sda3 7299 7664 2939895 82 Linux swap / Solaris /dev/sda4 7665 60801 426822952+ 5 Extended /dev/sda5 7665 10097 19543041 83 Linux /dev/sda6 10098 60801 407279848+ 83 Linux [neutron][02:34:12 PM] fdisk -l /dev/sdb Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdb1 1 121601 976760001 83 Linux
2009/01/23
Now I've gotten a WD10EADS to see if the performance will improve, and I copied the complete filesystem as-is, since the disk has exactly the same geometry:
neutron][10:47:06 PM] dd if=/dev/sdc of=/dev/sdb 1953525168+0 records in 1953525168+0 records out 1000204886016 bytes (1.0 TB) copied, 40451.8 s, 24.7 MB/s
so it's still ReiserFS. Heeeeere's Bonnie:
Version 1.93c ------Sequential Output------ --Sequential Input- --Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
neutron 6G 165 71 60356 30 27076 8 1285 87 58794 9 249.0 7
Latency 107ms 3227ms 1021ms 77159us 305ms 257ms
Version 1.93c ------Sequential Create------ --------Random Create--------
neutron -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 96 7 +++++ +++ 15349 81 902 79 +++++ +++ 12863 74
Latency 132s 10170us 9786us 44270us 20202us 37398us
yeah that seems like a pretty big improvement. And I don't hear the "swishing" noises the older drive was always making. I think that drive is defective.