OK. so here it is. But please remember these are my experiences over the last 3 years with EMC. YMMV. Things may have changed with the new NS600 series, but the basic arch is stll the same on their larger NAS systems. Behind all that hype, the Celera is still a piece of .... (well, they now have a Windows 2003 server based solution too, becasue they agree?) Don't get me wrong, I am not Anti-EMC or a Pro-NetApp. I am happy with their SAN so far.
Environment: Purlely CIFS based. H/W: Celerra (2 or 3 DataMover + 1 failover + 1 ControlStation, connected to a Symmetrix backend) in multiple sites
To summarize the EMC NAS architecture:
If you think about the Celerra solution you have a bunch of disparate components that are glued together to form the NAS server. It's a combination of many individual h/w units (at least the ones I have used so far). To get it all work is a challenge by it self. You need a data mover (couple if you need failover) a control station (again a couple if you need redundancy) , a FC switch (OEM from brocade/mcdata) to connect to the back end storage and then the backend storage itself (clariion or symmetrix). The datamovers are the equivalent of dedicated NFS/CIFS servers, and the control stations sit around doing out-of-band management and monitoring. The OS on the dmovers (DART) is a piece of crap, it still boots using MSDOS. The CS runs linux with many modified binaries/scripts to talk to the dmovers. You aren't getting a single solution here; it does all come in a couple of frames and EMC might set it all up for you initially (which would be a few months project) but any changes that you require will have to either be done by EMC or you're going to have to get in to all of the above horrible-to-manage areas to keep things running.
The problems I have had with the celerra so far: 1. It took EMC PS almost 6 months to get the thing installed working (under 10TB total NAS storage at multiple sites) and in the end they couldn't get it to work with NDMP and Netbackup. Suggested we backup over the LAN finally.
2. Needs a bin file change to add new disk or move volumes around. It took us 4 weeks to add few 100GB of storage at one site. Did I say we had to buy a new Dmover for this too? That thing is $50K a pop (all for a cheap PC that boots DOS first and then runs DART?).
3. The whole system would panic and shutdown if any of any of the data volumes fills up to 100%. (Note, not the root volume or tmp which is understandable, but the volumes you shared out). EMC's failover solution also does not work in this case. The Active datamover will panic and shutdown then the fail-over will kick in and panic too. It's not a one time incident, happened to us at least 4 to 5 times, at different locations. Wait till you hear their recovery procedure. We have to NFS mount the dmover volumes on to the control station and use unix to go in and delete files to recover some free space. Tell that to your Windows admins. What if your site has not unix admins? uh. We had a situation when their techsupport guy dialed in and deleted stuff that was important in a remote site.
4. Everytime Microsoft comes up with a new SP release there are problems connecting to the celeras. The current SP4 takes the cake! It panics the celeras. We had to sign support waivers with EMC because we were not ready to install their recommended patch the very same day they announced the problem.(Our past experiences with their patch/upgrades doesn't allow us to do whatever they recommend) We had the similar issue when SP2 came out, network performace used to be horribly slow, it took them 2 weeks to figure out the issue, that too after we pointed out that its only the machines with SP2 that are having this issue.
5. Each datamover had a limitation on how many volumes/shares it can support. There is no written documentation on this 9at least i haven't seen one), but their SE/Architect would not agree to create bin files with more that 4 volumes per Dmover in our environment. and each volume could not be over 200GB in size. Effectively limiting the capacity of a dmover to 800GB. They now tell us the new dmover (version5?) supports larger volumes (1TB), but still has a limitation of 4 TB per dmover. They say this has to do with fsck time. Try explaining this to the Windows guys. If their stuff is so reliable and redundant, why bother about fsck times?
6. OK so you wanted the Celera because it is a NAS solution. Then why do you need to have a SAN in between? If you need to hookup the celera to the backend storage, you will have to get a SAN fabric switch if the backend is Symmetrix. Even the Control station needs a FC port just to monitor something (if that link breaks, behold, the CS panics!). So if you have a fabric-attached unit then you still have all of the issues of zoning and LUN masking to worry about so that you can keep the disks seen by each datamover separate. Tell me once again, Why do I need this on a simple NAS that dishes out a few CIFS shares?
7. Their anti-virus solution. The CAVA agent and server would always crash, preventing users from accessing the shares. All AV vendors that I know of dropped support for their version of AV for Celera.
8. The infamous "UserMapper". Another piece of "value-added" crap from EMC. As per their manual, needed to map the Windows user logins to their equivelant Unix user IDs. It took me 2 weeks to explain this to our Windows support team, " please tell me gain, why do we need Unix logins to access a CIFS share?". It would have been OK if this damn thing worked. But.... you need 2 external Wndows machine to run an usermapper service that would hang and crash the server whenever it chose to, blocking users from accessing their data. Oh, so they made an improvement in the version 3, we could run it on the CS and didn't need those external windows boxes anymore. Good, but if you turn off the Control Station too long (remember it is just a monitoring station? nothing on it is in the criticle path of the data?), it turns out that users cannot login again because there is no user mapper. So in the end you bring up those old windows boxes again running user mapper... Well if you needed "that" kind of redundancy you shoudl have gone in for 2 CS was their answer. (BTW, I am told that the NS600 with clariion does not support 2 CS).
9. have you tried implementing quotas or snapshots on these ? Look at the user manual to see the what is involved, even a unix admin will faint.
10. Did I mention about their expensive GUI tool that the Windows guys could uses to "manage" the celerra? Well it sends out emails daily like these, can you help me figure this out ?: # # Celerra Serial Number: XXXXXXXXXXXXX, Control Station: # ************* Jan 22, 2004 6:34:17 PM ************* Alert: W0 ************* Jan 22, 2004 6:34:17 PM ************* Alert: W0 ************* Jan 22, 2004 6:34:17 PM *************
I could go on and on... but will rest my case here.
-G
----- Original Message ----- From: "Sto Rage©" Net_Backer@hotmail.com To: toasters@mathworks.com Sent: Thursday, January 22, 2004 2:32 PM Subject: Re: Migrating from NetApp to EMC Celera
Oh Boy! Did I create a storm in here!. I had many of you ask me for details. I am doing that right now. Will email you individually once
I
have compiled my issues. -G ----- Original Message ----- From: "Sto Rage©" Net_Backer@hotmail.com To: "Bruce Arden" arden@nortelnetworks.com;
Sent: Wednesday, January 21, 2004 8:52 PM Subject: Re: Migrating from NetApp to EMC Celera
I don't work for NetApp. But first ask what features would you
GAIN
by
migrating to a Calera. You loose so many features, the first being the simplicity to
manage
them.
We just moved all of our NAS storage off Celeras to NetApps
because
of
the so many issues. Email me directly incase you need more info. -G
----- Original Message ----- From: "Bruce Arden" arden@nortelnetworks.com To: toasters@mathworks.com Sent: Wednesday, January 21, 2004 10:44 AM Subject: Migrating from NetApp to EMC Celera
I have been asked what the problems would be migrating from
NetApp
filers to EMC Celerra. Has anyone had any experience of doing
this.
What features would I loose?
- Bruce
-- Bruce Arden arden@nortelnetworks.com barden2@csc.com CSC, Nortel, London Rd, Harlow, England +44 1279 40 2877