Dobrica Pavlinušić's Weblog / Blog

In my continuous quest to endless disk storage, I have ordered two D-Link DNS-323 NAS devices. Since this is my second NAS device (first was DSM-G600 which is PowerPC) I have some experience, so let's see what is inside this (big, black, heavy, metal) box.

dlink-DFDADE:~# uname -a
Linux dlink-DFDADE 2.6.12.6-arm1 #30 Mon Aug 18 14:19:14 CST 2008 armv5tejl GNU/Linux

dlink-DFDADE:~# free
            total      used      free    shared   buffers    cached
Mem:        61904     54808      7096         0     11824     30592
-/+ buffers/cache:     12392     49512
Swap:     1060208         0   1060208

dlink-DFDADE:~# cat /proc/cpuinfo 
Processor      : ARM926EJ-Sid(wb) rev 0 (v5l)
BogoMIPS       : 331.77
Features       : swp half thumb fastmult edsp java 
CPU implementer : 0x41
CPU architecture: 5TEJ
CPU variant    : 0x0
CPU part       : 0x926
CPU revision   : 0
Cache type     : write-back
Cache clean    : cp15 c7 ops
Cache lockdown : format C
Cache format   : Harvard
I size         : 32768
I assoc        : 1
I line length  : 32
I sets         : 1024
D size         : 32768
D assoc        : 1
D line length  : 32
D sets         : 1024

Hardware       : MV-88fxx81
Revision       : 0000
Serial         : 0000000000000000

So, it's a 330 Mhz ARM with 64Mb or RAM (expandable to 128Mb with SMT soldering, sic!) and a disk. D-Link provided firmware has oldish 2.6.12.6 kernel and usb modules just for printer support. Even worse (than usb keychains or wifi dongles not working) is RAID performance: in RAID0 (which is called performance by firmware) I get 32 Mb/s from single disk and just 37 Mb/s from stripe.

But, all is not bad, because we can install full Debian on DNS-323 which brings us latest software which is just apt-get away, LVM, and support for various recent hardware.

After flashing, and updating to latest Debian arm kernel for orion platform I got 44 Mb/s from single disk and 42 Mb/s from RAID0. So I'm really hitting some bus bandwidth problem somewhere... Even worse, RAID1 is just 36 Mb/s, suggesting that 330 Mhz arm just can't keep up with pair or 1.5Tb SATA drives connected to it.

Next logical step would be to think about a way to use drives individually, because aggregating them on device doesn't make sense. With 220 Mb/s bandwidth on network (which is supposedly 1 Gb/s, sic!) it should be possible to get 44 Mb/s of disk speed onto another machine. I tried vblade which provides AoE server in user-space and it's slow: just 8 Mb/s to directly connected ThinkPad over cross cable.

I will test NFS (and CIFS if everything else fails), but I can guess that I will end up using this device for incremental backup dumps on top of ext4 or maybe nilfs. We'll see...

Update: I didn't choose DSM-323 randomly. When I was deciding which NAS device to buy, I watched Debian on Network Storage Devices and Other Devices which is embedded below for your viewing pleasure (download hi-res version). Orion related stuff starts at about 13:50.