org geek recommendation please DAS Vs NAS

[timwilky]

My home vmware server needs more storage. the internal slots are full with 6 expensive 2.5" SAS 15K 73GB so I need an external solution.

Options are :-

iSCSI off a NAS. Or I go for a DAS solution.

I have never used iSCSI so what is performance like?

So I am nudging towards DAS. I know I can get eSATA cards that support 6GB SATA III standards. But I cannot find a DAS enclosure that will support a SATA III interface.

So come on geeks, recommend me a solution. Remember this is for my home setup so I need to be able to hide this from the domestic finance controller.

[Fruity-ya-ya]

Remember this is for my home setup so I need to be able to hide this from the domestic finance controller.

My face is sore from laughing and must look like a right burk as i'm still giggling like a fool in the staff canteen.
Can't really offer any useful advice but wanted to thank you for brightening up an otherwise sub-par Monday.

[Bibio]

just dump 2 of the 2.5's and install 2x2tb 3.5 SATA3's the difference in performance will be very very small.

[fizzwheel]

Its been ages since I looked at iSCSI properly.

We had it setup for our QA / DEV environment

1. It was a complete utter ball ache to get it working properly alot of it was to do with the CHAP authentication being problematic to get working, ( but I suspect this was down to the fact the NAS we were using wasnt that good )

2. When I did get it working the performance was poor ( again I suspect this down the NAS )

We've recently set it up again, but with iSCSI disks presented to a W2K8 server with no Vmware / Hyper V in the equation.

Performance seems a lot better now and it was straight forward to get working.

I must admit since that I have been a bit wary of iSCSI. IIRC the recommendation from Vmware is / was to have a dedicated NIC for your iSCSI traffic as well.

In your shoes I'd be looking for something DAS.

[timwilky]

just dump 2 of the 2.5's and install 2x2tb 3.5 SATA3's the difference in performance will be very very small.



all my slots are 2.5", it is a 1u chassis DL360 G5. The six drives are configured as a raid 5 with 1 hot spare. So I could in theory dump 2.

But can I swap say 1Gb 2.5 sata in the same backplane as the SAS?

Research would say it would only support 1.5Gb throughput so not a good way forward.

[kaivalagi]

If you went the NAS route is there any reason why it has to be iSCSI based? Do you want to run guest OS's from the iSCSI space? Or is it just a basic preference for NAS based storage?

I have a decent domestic NAS at home giving me 9TB of space over raid 6 (5 sata III bays, with up to 2 swappable at any one time), I have 1GB of space preserved for iSCSI usage which is useful for VMs and having a "local" drive for some things, but I do tend to use standard Samba and NFS shares for the majority of my data storage needs.

I tried a Thecus NAS which was awful, data corruption for no reason even after firmware updates of the drives etc, I ended up spending a little extra and getting a Synology 1512+ and putting 5 x 3TB SATA drives inside, at < £100 each it works out okay per MB.

The bonus of having this NAS is that I can also use it to access the "desktop" over the net and on my phone, download/upload data over the net in a specified area, stream video via uPnP, manage downloads / bit torrents on the box freeing up the TCP/IP stack on my other PCs and allowing queuing of download tasks remotely/over the net, have a bunch of Android tools to access it's features etc etc

It really does depend on what type of data you plan on storing on a DAS/NAS and how you want to access it and the performance you NEED

If you want a domestic NAS I recommend a Synology anyway...zero problems in the approx year I've been running this one constantly...and if you need more space this NAS allows a bolt on expansion of a further 5 drives in another 5 bay unit (cheaper) which connects to the first via eSATA

Hope that helps

edit: the synology site has a demo of the "desktop" (http://www.synology.com/products/dsm_livedemo.php?lang=uk) on the NAS to see what you would be getting...

[timwilky]

Exactly, I need to install guests on the external storage. So it has to be visible to ESXi

At first I was thinking fine just hook up a usb3 device. But research would suggest that ESXi cannot see USB3. Hence going for an eSata device, even if that would only deliver 3Gb, which in truth should be fast enough.

Is there a performance trade off to iscsi. the appeal of a single device to provide traditional file storage as well as holding guest O/S is appealing. Worst case would of course be putting all eggs in one basket if corruptions are possible.

[kaivalagi]

Is there a performance trade off to iscsi. the appeal of a single device to provide traditional file storage as well as holding guest O/S is appealing.

In theory it's just down to the speed / quality / contention of the connection, the protocol is sound.

If you are comparing a 1GB ethernet based iSCSI connection to a 3GB eSATA connection it will obviously be slower...but I doubt it's as much as these figures suggest. For eSata 3Mb/s throughput is far fetched. I'd say you will see top speeds of more like 900 Mb/s for random file access. That isn't that far off from iSCSI over 1GB ethernet assuming you have a dedicated broadcast domain for that connection.

Do you know anyone who can let you trial thier NAS over iSCSI to see if that would be enough for you? Probably the best bet in my mind, a nice practical test before you spend money....

edit: may there are NAS out there allowing both connection types? So you have some flexibility? I've never gone looking for this so aint sure if there is anything like this or not...

Worst case would of course be putting all eggs in one basket if corruptions are possible.
Raid6 gives 5 drives with the possiblity of 2 failing and still retaining data, plenty good enough to me...but as always backups from even this are still valid. I use older spare drives with a SATA <-> USB adapter to store important data on and then turn them off and put them in a drawer out of the way and unused...

[Teejayexc]

If you went the NAS route is there any reason why it has to be iSCSI based? Do you want to run guest OS's from the iSCSI space? Or is it just a basic preference for NAS based storage?

I have a decent domestic NAS at home giving me 9TB of space over raid 6 (5 sata III bays, with up to 2 swappable at any one time), I have 1GB of space preserved for iSCSI usage which is useful for VMs and having a "local" drive for some things, but I do tend to use standard Samba and NFS shares for the majority of my data storage needs.

I tried a Thecus NAS which was awful, data corruption for no reason even after firmware updates of the drives etc, I ended up spending a little extra and getting a Synology 1512+ and putting 5 x 3TB SATA drives inside, at < £100 each it works out okay per MB.

The bonus of having this NAS is that I can also use it to access the "desktop" over the net and on my phone, download/upload data over the net in a specified area, stream video via uPnP, manage downloads / bit torrents on the box freeing up the TCP/IP stack on my other PCs and allowing queuing of download tasks remotely/over the net, have a bunch of Android tools to access it's features etc etc

It really does depend on what type of data you plan on storing on a DAS/NAS and how you want to access it and the performance you NEED

If you want a domestic NAS I recommend a Synology anyway...zero problems in the approx year I've been running this one constantly...and if you need more space this NAS allows a bolt on expansion of a further 5 drives in another 5 bay unit (cheaper) which connects to the first via eSATA

Hope that helps

edit: the synology site has a demo of the "desktop" (http://www.synology.com/products/dsm_livedemo.php?lang=uk) on the NAS to see what you would be getting...


Wtf did you just say :confused::smt017

[kaivalagi]

Wtf did you just say :confused::smt017
I thought it made sense, NAS is good, lots of bells and whistles, plug one into your router and windows 7 / linux / MAC will likey :)

[SoulKiss]

Tim, everything you NEED to keep can live on an external USB 3.0 drive, or in The Cloud somewhere (suitably encrypted of course)

I had a 4TB RAID5 array, then had a long look at it and my requiremends and have now replaced it with a £100 HP Microserver with 1x3TB WD RED SATA drive in it, set up for LVM (except the boot partition and swap file)

I figure I have less than 30GB of data I cannot aford to lose, so my 2TB USB2.0 drive will more than handle that, and I can do backups to S3 for extra security.

Why would anyone need SAS drives at home - I mean REALLY do you need them?

When prices drop further or I upgrade one of my SSD's I'll chuck the spare 120GB one in an external USB3 cadfdy (I'll probably get another Zalman VE-400 which does hardware encryption if you want (for £50) and that will be fine for my "cant loose this" backups.

I just figured I no longer needed loads of resilient storage - and if I need more, I have 3 spare 3.5" slots in my server that I can just add to the LVM...

Oh and the server is also terminating my PPPoE and acting as my router - only fly in ointment is getting my PDCE Wifi card working - bougth one that *just* too new...

[keith_d]

If you're planning to run VMs on your storage I'd go for direct attach over iSCSI.

Most SOHO iSCS| implementations use general purpose network chips and implement iSCSI in software on the same low power CPU that's running software RAID. It's rather different from the commercial implementations where the iSCSI HBA has most of the TCP stack running in silicon and connects to a custom iSCSI chip in the storage system. Even with all that expensive hardware we see performance problems running large VMware environments over iSCSI.

I had a quick goodle and you can get a 4 disk eSATA enclosure for less than £100. (http://www.maplin.co.uk/4-bay-terabox-esata-hdd-raid-enclosure-224358) Though you would need to look at the VMware HCL to be sure the eSATA interface is supported.