A minimal CloudStack deployment has one zone, one pod and one cluster running with a single shared NFS primary storage. The shared storage hosts the virtual disks for all instances running on the same cluster.
Multiple instance of different types and workloads are hosted on the same cluster. Instances running disk bound workloads like database services compete with instances running CPU/Memory bound tasks like application services. This can lead to unpredictable IO performance as instances are competing for the same shared disk resources. As load increases on the storage server, disk performance on all instances start to degrade.
Continue reading CloudStack And Primary Storage NFS Performance
The DS210j is described as a Budget-friendly 2-bay NAS server for Home and Small Business. If the DS210j is considered to be basic, then I wonder what you would call my ageing Airlink101 NAS 350 then??? 🙂 Anyway, I have been a heavy user of this device since April 2010 and is probably a nice time to write a quick review.
The objective of upgrading from the Airlink101 to the Synology are as below:
- Go Green Initiative: Needed a very quiet low power device to store data at home
- Data Protection: I get jittery with data. The 2 disk RAID1 mirroring I hope will guard against total data loss in case of a single disk failure
- Hardware Support: Things do go wrong and having a place to get it fixed would be nice
- Software Support: Most embedded devices these days are Linux based. But very few companies are serious about providing s/w updates. A quick check on the web reveals that the Synology Disk Station Manager is a very well supported platform and also has iPhone access methods. These days, I make sure that all my devices work with the iPhone
- Local Pricing: The device should have a pricing that makes sense for local purchase in India
- DLNA: Streaming (atleast non-HD sources) to various other devices I have at home like the iPhone, iPod, Denon AV receiver, laptop etc
- Performance: Enough throughput to saturate a 100 Mbit Ethernet link. DS 210j is able to do that according to the performance graphs
- Shell/Web Interface: Ability to ssh into the node or use a web interface from the Internet is a must
- Torrent: Schedule torrent downloads from anywhere. I don’t want to rush back home to d/l the next episode HD of anything
- Storage: Ability to use the biggest disks available in the market; 2TB at the time of purchase
- UPS Support: Need to shutdown cleanly before the UPS runs out of reserve power. The power cuts in Bangalore are getting worser by the day
- Backup: Backup using Apple Time Machine automatically
Please do keep in mind that the DS 210j is powered by a lowly 800Mhz ARM926EJ CPU with only 128MB of RAM. So how well does it work in real life?
- Performance: Its very very easy to overload the low power CPU on this unit. Two simultaneous active torrents is the maximum I can squeeze out of it. The 128MB RAM is also a limiting factor. I have seen it hit swap often. But none of these really mattered as am limited by my 2Mbit uplink and a G class wifi network which anyway restricts me to very low file transfer speeds. Both the 1.5TB WD Caviar Green disks are working well in RAID1 Mirroring mode. The system has recovered cleanly from both clean and unclean shutdowns due to power cuts. The system loads are quite high during the raid sync operation after a unclean shutdown but thats OK; I haven’t see any operational issues when that happens. In terms of actual disk I/O, I can do 15MB/s when copying over the USB interface. It’s probably limited by the transfer rate of the portable USB disk than the Caviar Green HDD.
- Usability: I absolutely love what the Synology Disk Station Manager lets me do. The web interface is very slick for setting up system configs and viewing status. Also useful is the streaming player that allows for listening to your music from the Internet. I already have dynamic DNS setup with port forwarding that makes it easy to do this. The iPhone app for photos and music which is available for free via the Apple App Store makes it a pleasure for streaming stuff out. iTunes too works well for streaming. Setting up Time Machine to automatically backup to the device was a breeze. My laptop backups now happen like every hour when am connected to the home network.
- Addons: To be able to ssh to the device, add additional packages via ipkg (mrtg, mc, mutt etc) is making it all the more easier to have a well managed home network. Sometimes I forget that it’s a low power embedded device that am doing all this on.
What it cannot do (and the feature I want most) is the ability to transcode. Though transcoding tools are available via the package repository, 800Mhz of CPU horsepower would not suffice for real time HD streaming. I plan to solve this by getting a Mac Mini soon and having it mount the shares. The DS210j’s position should really be of a dumb storage device and have more powerful devices take care of the macho stuff like streaming/torrents.
Bottom line – I am not the typical “home/small office” user. For my needs, I should have looked at a desktop class performance which is provided by the higher end Synology models. Given the cost constraints, I find the DS210j as an acceptable compromise. But for most real home users out there, this just might be the no headache/low maintenance storage device you are looking for.
Amazon link at http://www.amazon.com/review/R3BVH7K7NVZF11/ref=cm_cr_rdp_perm