need advice: slow IO on eSATA WD MyBook compared with ext. ATA MyBook.

I wonder if anyone has had experience with WD MyBook drives, where older ATA drives are faster than newer eSATA drives?

I have one 320GB WD Mybook with 1394-a and USB2 interface. I have it connected using 1394-a to an Acer Aspire laptop used as file server running CentOS 5.2. The disk is one big dmcrypt'ed partition using ext3. The tests below are all done on firewire for this drive, but in the past I have tested USB2 and it was actually slightly faster than firewire.

I bought some new drives in June, 2 new WD MyBook 500GB drives (the mac version) which came with a triple interface; USB2, 1394-b and eSATA.

I bought a Silicon Image 3512 controller PCMCIA card with 2 ports, and connected them both to that controller. I set them up as a RAID-1 mirror array with mdadm and them encrypted the whole ext3 partition with dmcrypt. I had a few problems with this setup, where the disks tended to flake out if they went to sleep, and mdadm would give up and take out one of them from the array; then resync times were measured in days not hours. I also had problems where the ports would hang during boot or shutdown, and this made it basically unusable. I "solved" this by running a cron job every 3 minutes to 'ping' the drives with sdparm, and I powercycle the 2 drives just before bootup to solve the problem of them hanging (the activity light on the pcmcia card would stay lit indicating it had hung).

This has been working ok since july, and I have discussed these issues on this list, and recieved a patch, which I am ashamed to say I have not had time to try yet.

But now, I have finally gotten around to performance testing the drives and it is a disaster! The eSATA RAID-1 array is running awful compared to the older ATA 320GB drive. My tests are below. I do not know if I have tested correctly, and I am aware there will be a write penalty for RAID. My question is: Does this seem weird? What speeds should I get for eSATA? Why does a SATA drive on a USB2 interface run much slower than ATA drive on USB2 interface (note: i tested firewire, but 320GB on USB has run faster than firewire)? Why are the 500GB RAID-1 drives on eSATA controller running at 15MB/s!!! and same RAID-1 array, plugged into USB2, suddenly jumps up to average of 27MB/s? I have not tested the RAID-1 array on 1394-a yet, as I do not have a 1394-b to 1394-a adapter, but I intend to test this as well. Do I need to "tune" SATA drives in the same way one had to tune older ATA drives? For example, You used to have to enable DMA on ATA drives, but with sata it's enabled by default, but is there anything else similar to this that needs setting with hdparm/sdparm to get "normal" performance?

##### Firewire 400 Write test on WD 320GB dmcrypt ext3 #####

[root@k2 mnt]# /usr/bin/time dd if=/dev/zero of=/mnt/mybook320/upload/test count
=393216
393216+0 records in
393216+0 records out
201326592 bytes (201 MB) copied, 6.28506 seconds, 32.0 MB/s 0.23user 3.82system 0:06.40elapsed 63%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+218minor)pagefaults 0swaps

##### eSATA (sata_sil 3512) Write test on WD 500GB dmcrypt ext3 #####

[root@k2 mnt]# /usr/bin/time dd if=/dev/zero of=/mnt/raid500/upload/test1 count=
393216
393216+0 records in
393216+0 records out
201326592 bytes (201 MB) copied, 13.3667 seconds, 15.1 MB/s 0.23user 3.52system 0:14.58elapsed 25%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (2major+215minor)pagefaults 0swaps

##### eSATA (sata_sil 3512) Read test on WD 500GB dmcrypt #####

[root@k2 ~]# /usr/bin/time cp /mnt/raid500/upload/test1 ./ 0.04user 2.39system 0:16.72elapsed 14%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (3major+212minor)pagefaults 0swaps

##### Firewire 400 Read test on WD 320GB dmcrypt ext3 #####

[root@k2 ~]# /usr/bin/time cp /mnt/mybook320/upload/test ./ 0.02user 1.55system 0:09.44elapsed 16%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (4major+209minor)pagefaults 0swaps

#######################################################
USB interface tests

##### USB2 Write test on WD 320GB dmcrypt ext3 #####

[root@k2 Desktop]# /usr/bin/time dd if=/dev/zero of=/mnt/mybook320/upload/test c
ount=393216
393216+0 records in
393216+0 records out
201326592 bytes (201 MB) copied, 5.30326 seconds, 38.0 MB/s 0.21user 3.29system 0:05.78elapsed 60%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+217minor)pagefaults 0swaps

##### USB2 Write test on WD 500GB dmcrypt ext3 #####

[root@k2 Desktop]# /usr/bin/time dd if=/dev/zero of=/mnt/raid500/upload/test1 co
unt=393216
393216+0 records in
393216+0 records out
201326592 bytes (201 MB) copied, 7.40847 seconds, 27.2 MB/s 0.18user 3.21system 0:07.69elapsed 44%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (2major+214minor)pagefaults 0swaps

##### USB2 Read test on WD 320GB dmcrypt ext3 #####

[root@k2 Desktop]# /usr/bin/time cp /mnt/mybook320/upload/test ./ 0.01user 1.58system 0:08.86elapsed 18%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+213minor)pagefaults 0swaps

##### USB2 Read test on WD 500GB dmcrypt ext3 #####

[root@k2 Desktop]# /usr/bin/time cp /mnt/raid500/upload/test1 ./ 0.02user 2.42system 0:12.13elapsed 20%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+213minor)pagefaults 0swaps

--andrew

1.) The advice: get rid of WD MyBook Studio Edition
2.) they suck (I own one myself)
3.) they suck (google around... I can dig up some links if you want) 4.) You could use them over USB. I guess it is the only interface that works reliably. I had sometimes below 10 MB/s transfers with Firewire. 5.) currently I use an exchanged drive. The first one never exceeded 40 MB/s over eSATA.
6.) Just get rid of it ;-)

Some links:
- "WD MyBook Studi doe snot work over eSATA with linux"
http://bugzilla.kernel.org/show_bug.cgi?id=9913#c26

Regards,
David Balažic

PS: You get 38 MB/s write on WD 320GB over USB ? That is "rekordverdächtig" as the Germans would say. (in english "recordsuspicious", I would emphasize the "suspicious" part myself.