Sata VS USB on Pro

[slycat]

BestBuy has for the BF weekend a 3TB external USB 3.0/2.0 Goflex Desk drive for $99. I know GoflexDesk does not have any accessories to dish out eSata. So I open it up and see its the Barracuda XT sata drive, figured I could buy an enclosure and get a eSata-to-Sata cable with the same ole setup (5/4/leftover OS/Swap/Storage). Or stick to the lazy way out and just plug it in via the USB port.

My question: to those of you who have their drives connected to the internal Sata, do you find a great difference in speed compared to USB? I will only be using it for file/print serving and media streaming, but I fear that the bottleneck comes in due to the pro's 700MHz speed, not the interface. Will plugging in via Sata make a difference in media streaming or file sharing? I know WHSE has had great speeds through samba compared to using USB and leming mentions I/O waits with USB, but they are also wizards . What kind of speeds are the rest of you getting?

tl;dr
>Is it worth buying an enclosure and cable to connect to Sata or just stick with USB?

[Geoff]

Testing sequential write and read on a Seagate Momentus 320GB 7200RPM 2.5" drive, at the outer edge of the platter (where the head flies fastest), using dd to write 1GB from /dev/zero to a file and to read from the file to /dev/null, using (best-case) block size of 512KB, I got the following results:

SATA write: 45 MB/s, SATA read: 98 MB/s, USB write: 20 MB/s, USB read: 28 MB/s

The SATA speeds are about the same as I get using the eSATA of my pretty decent laptop (IIRC, though maybe the laptop was somewhat faster writing), so I imagine these are the top speed of the drive and not limited by the SATA interface. I think it might be more interesting to measure the speed of read/write patterns that occur in typical swap-space use, but I don't know how to simulate that.

The drive enclosure that I am using is a "Vantec NexStar 3" that comes with an eSATA cable, a USB cable for data and/or to power the drive while using eSATA, and (bonus!) a ribbon cable for connecting the internal SATA to eSATA that I installed inside the PogoPro. I neatly drilled and filed a place next to the ethernet socket to mount the eSATA socket. If you do this, be careful to trim away the plastic rib inside the case opposite the SATA socket, because the plug is straight (not right-angled) and the rib will bruise the cable otherwise. I imagine yours is a 3.5" drive, so you would need a different enclosure and power source; I describe my setup in order hopefully to help others who are thinking about using a 2.5" drive.

Edit: I just checked the Vantec website, and I'm not sure that their newer enclosures come with a SATA to eSATA cable; apparently it comes only with their older model NST-260SU.

[slycat]

Thanks, Geoff. Nice to see statistical evidence rather than "yeah, it's hella faster"
Is your boot on that drive, too? Like did you run the test once when plugged to sata then reboot when plugged into usb to try again? Or is your boot on another drive and you were hotplugging your testing drive?

Well keeping in rhythm with BF sales, NewEgg has a 3.5" Rosewill enclosure with cables and internal fan for 50% off. Thanks for the suggestion of the Vantec models though. I don't have a drill to make a neat cut but I am sure I can MacGyver the space to fit the sata plug.

[WarheadsSE]

Oh, it's a noticeable difference, especially with swap-hungry apps.

I used to have a document on the wiki on how to add it, and where I got the parts but Geoff covers the gist. I used no drills :p Exacto knife, patients and a soldering iron (that happened to be the exact size of the screws)

[slycat]

Swap is a concern. Transmission gobbles a ton with multiple peers connected and conflicts with minidlna streaming even 720p files. I just wanted to be sure the extra work/money would be worth it or if the CPU speed would be the limiting factor. I have purchased the Rosewill enclosure, should be here sometime next week but won't be up until after finals, sadly.
Now that you're on the topic, Warheads: If switching from USB boot to Sata boot, must I restore the plug to factory setup and then run the setup script again, or will the first partition of the sata drive be read as rootfs without going through the revert? Sorry if this has been addressed before, couldn't find any post on the matter.

[Geoff]

$this->bbcode_second_pass_quote('slycat', 'I')s your boot on that drive, too? Like did you run the test once when plugged to sata then reboot when plugged into usb to try again? Or is your boot on another drive and you were hotplugging your testing drive?

[WarheadsSE]

Okay!

If you are going to use a `cp -ar` then you will need to do it as root, from a non-running instance. Aka, don't try to backup a running install from inside itself with cp -ar. You may however:
- extract a fresh rootfs (latest of course) onto the SATA drive
- chroot into that new filesystem
- pacman -Syu
- pacman -S mysql transmission minidlna [etc etc etc]
- copy any working data/configuration/fstab etc
- reboot

The SATA drive will always come up as /dev/sda1 as well, so that removed the usb booting issue entirely.

And technically, hotplug does work, sorta You just have to wait for the system to be fully booted, attach the SATA drive, and run a certain command to tell it to re-scan the SATA port. Port multipliers however, seem to be cause more issues, as the stage1 in-chip code to load the stage1 bootloader doesn't know about port multipliers, but detects presence on the SATA port, pissing off the boot process.

[slycat]

Great! I've had my plug do auto-backups for some time and figured I would decompress the gz to the new drive once I get it to it's new enclosure. I've done it before with zero problems (knock on wood) but I'll try the other methods you mentioned, WHSE, should my backups crash and burn. I will cp -ar my storage partition though, probably do that now since it'll be 500+ gb being shoveled through the USB port.

I appreciate the benchmarking, Geoff. I've been meaning to switch for a while but only if it was a real improvement and not some placebo, heh. The new enclosure sports both USB and Sata so I'll test my own r/w speeds.

Hotplugging would be useful should someone boot from a non-journaled flash drive and have Sata as their swap/storage, right? But keeping all three partitions (boot/sw/storage) via Sata isn't bad either? For what I use it for, I don't need blazing speeds, but if I could put the rootfs on a flash drive as ext2, limit the number of writes to it and lessen the load on the Sata port to keep swap up to speed wouldn't be a bad idea (if feasible or theoretically correct). Guess that'll be another benchmark I'll try out once my brain cools off from finals week.

[WarheadsSE]

Theoretically, with some fstab magic you could do that, but for the if you wanted to boot off the usb, and have sata connected, you'd have to change some uboot parameters, and deal with not knowing the order the usbs are picked up for certain.

[emkay]

Hi there,

I have an external disk enclosure for 4 HDDs with USB and eSata ports. I use the pogoplug pro at the moment with alarm and the USB Port.

If I want to use the eSata port of the enclosure, the corresponding port on the device must support port multiplying if I want to access all 4 disks.

Does anyone know if the Sata-port on the pogoplug pro supports port multiplying?

Thanks for your help!

EmKay