Drobo
The drobo showed up yesterday. The unboxing was as cool as with an Apple product. And it is really easy to setup and start using... as long as you are plugging it into a Mac or PC. The instructions don't say anything about how to get it to work on Linux. Luckily I found this via google:
[root@192.168.1.1]# lshw
[root@192.168.1.1]# /sbin/mke2fs -j -i 262144 -L Drobo -m 0 -O sparse_super,^resize_inode -q /dev/sdc
[root@192.168.1.1]# mkdir /drobo
[root@192.168.1.1]# mount -t ext3 /dev/sdc /drobo
[root@192.168.1.1]# vi /etc/fstab
/dev/sdc /drobo ext3 defaults 0 0
That was all I needed to get me going.
I thought I had a bunch of old hard drives lying around that I would be able to wedge into drobo until I could afford to buy real drives, but none of them are SATA. Darn. Another bummer is that my server has a firewire plug that is heart-shaped and resembles a mac firewire, but the firewire plug on drobo is square. So I think I'm stuck with USB. My first speed test writing to drobo shows 14.8MB/sec. That feels pretty lame.
Another weird thing is that the drobo shows the full capacity of the array, not the actual capacity. That is, I put two 1TB drives in it and it looks like this with df -h:
/dev/sde 2.0T 155G 1.9T 8% /drobo
I expected drobo to report the capacity of the array to be about 1TB instead of 2TB.
I added a few more drives to the drobo to give it the capacity to hold our vacation videos.
drobo performance on usb 2.0
But still the drobo is just too slow. How slow is it? Bonnie says this:
rday@weasel:/drobo/bonnie$ bonnie
Writing a byte at a time...done
Writing intelligently...done
Rewriting...done
Reading a byte at a time...done
Reading intelligently...done
start 'em...done...done...done...done...done...
Create files in sequential order...done.
Stat files in sequential order...done.
Delete files in sequential order...done.
Create files in random order...done.
Stat files in random order...done.
Delete files in random order...done.
Version 1.96 ------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
weasel 6G 249 74 1019 0 500 0 876 63 1111 0 58.3 2
Latency 1516ms 21811ms 1552ms 76164us 261ms 727ms
Version 1.96 ------Sequential Create------ --------Random Create--------
weasel -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 1387 6 +++++ +++ 1815 4 1615 4 +++++ +++ 1811 4
Latency 63932us 1261us 725us 2761us 2696us 121us
I care most about block reads and writes. Those come out at 1111 and 1019 K/sec.
native internal disk performance on the same machine
Compare that to bonnie running on an internal drive on the same machine:
Version 1.96 ------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
weasel 6G 347 98 33362 24 17006 10 1311 95 46774 13 115.1 7
Latency 83296us 2552ms 1958ms 97333us 412ms 1399ms
Version 1.96 ------Sequential Create------ --------Random Create--------
weasel -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 2238 86 +++++ +++ +++++ +++ 2691 97 +++++ +++ 6854 97
Latency 35917us 410us 319us 53088us 119us 874us
That means block reads and writes at 46,774 and 33,362 K/sec. About 30 times better.
But if I just need to find the right firewire cable to switch off of USB, then I'm a dummy for using USB all this time.
Wikipedia says that USB 2.0 generally performs at 240Mbit/sec and 1394 does 400Mbit/sec with less CPU load. I've got to find that cable.
Hopefully, I'll be able to post bonnie stats for drobo over firewire soon.
