Mirror or Clone?

[eprepguy]

I have a Mini with SLS and two internal 500GB drives. I wont be using any internal storage for the server
What would you say is the advantage to setting up the boot drive as a RAID1 mirror instead of just scheduling a cloning every night to the other drive?
Any pros and cons to either method?

 

[TechnoDestructo]

No difference.
Except....

With a Raid the changes are instant. If something or someone screws up a file there is no going back.
With a nightly backup you have a chance to recover the file(s) or restore the main drive.

 

[philipma1957]

I have a Mini with SLS and two internal 500GB drives. I wont be using any internal storage for the server
What would you say is the advantage to setting up the boot drive as a RAID1 mirror instead of just scheduling a cloning every night to the other drive?
Any pros and cons to either method?

clone from drive a to b every night and clone to an external once a week

 

[eprepguy]

Yes, I am more familiar with cloning than I am with R1 mirror setups. Not that I dont know how, its easy, but my main question has to do with what happens when there is a drive failure? With cloning I know exactly what will happen, The primary boot drive fails, the computer crashes, the computer reboots using the (now) only boot drive available, which is the clone. Next steps are all about ordering new drive, installing...etc.
But with a R1 mirror setup, I am not sure what happens after a single drive failure. Does the computer crash or instantly switch to the mirrored drive? Does the computer crash and will not restart until i replace the mirror? I just dont know. Also, thats an excellent point about the mirror is subject to any operator error or virus that happens to the primary. So it seems to me to be a better plan and more familiar to me if a drive failure occurs, to simply clone every so often to the other drive, and keep an offsite copy just in case something happens to both a and b.

 

[philipma1957]

with raid1 the mirror takes over and you get a warning that 1 drive is dead put a blank replacement in. mirror works better with easy access to hdds and if you are running a website or any type of work that can't be stopped. clone is better for the avg user. two or three clones, a mirror , a time machine and offsite is gold standard.

 

[eprepguy]

with raid1 the mirror takes over and you get a warning that 1 drive is dead put a blank replacement in. mirror works better with easy access to hdds and if you are running a website or any type of work that can't be stopped. clone is better for the avg user. two or three clones, a mirror , a time machine and offsite is gold standard.

Thanks, philipma1957, do you mean that the sytem just keeps on truckin like with a UPS when the power goes out? If so, I would consider that a definite "pro" to mirroring if you need that sort of thing. Not sure yet which I'd prefer, I will use this mini solely as a file server and backup system for my photo studio which has about 10 macs on the network. We can easily suffer a momentary loss of the server and have done so for years with our current system, JBOM (Just a Bunch of Macs) Is there a way I can tell the mini to email me if a drive goes out?

 

[philipma1957]

yes in theory the mirror will keep you running without a stoppage. Of course in the mac minis case you will need to replace the hdd that died soon, but more at your timetable. An email raid failure warning is possible I have not setup a mirror raid in a mini. I did it in an external with external software it was all sans digital gear I used their software to send me an email.. Give me a day I will look for the option on snow leopard mac mini raid software this thurs.

 

[Vassius]

Thanks, philipma1957, do you mean that the sytem just keeps on truckin like with a UPS when the power goes out?

Yes, your system will be operational as long as one of the mirrors is running. RAID mirroring is transparent to the OS, so the system is not affected by one failed drive. Only drawback is obviously that you lose your redundancy if one drive fails, so the faulty drive should be replaced asap. When it's replaced, the RAID mirror will be automatically rebuilt.

 

[philipma1957]

I did some checking and if you use apple raid0 utility it does not send a warning email. you would need to look into an external case from a company like sansdigital that has its own software for raid.

 

[eprepguy]

Thanks, everyone! very helpful info. I have decided that for my needs here that I will set this up as a standard single drive boot and clone to the second drive and offsite backup. I will use existing FW800 port for DAS R5 boxes. I am curious as to how this Macmini server will handle our traffic load at the photo studio (10macs, about 50-100GB's new data per day) and will start a new thread to discuss various options for increasing its performance as a file server for my biz (ie: ssd drive, increase RAM, 2nd ethernet port for iSCSI, ftp so I can work on files from home...stuff like that)
But for starters, I will set up as is. I really have no need for two 500GB notebook drives, since it is a server, I wish it had more high speed ports like eSATA, TBolt and stuff like that; but I am hoping it will be a major improvement over my JBOM scenario that we currently use. I know they will probably be coming out soon with the new version with some or all of those improvements, but I am never an early adopter kindve guy. We shall see!

 

[Nanker/Phelge]

Why not go RAID0 on the internals for the performance boost with an external set to clone on frequent intervals?

 

[talmy]

Why not go RAID0 on the internals for the performance boost with an external set to clone on frequent intervals?

This is exactly what I do. I don't need the no down time assurance of RAID1 and was after as much performance out of these notebook computer drives as I could get. I've got an automated backup to an external that runs every night that I swap with one offsite every week.

 

[eprepguy]

Why not go RAID0 on the internals for the performance boost with an external set to clone on frequent intervals?

Yes, ZRD, am thinking of that as well. Since the boot drive will be backed up externally, why not, right? I started a new thread on possible upgrades andor mods that will improve file service performance and thats a good point to add. For instance, if I get a performance boost from R0, maybe SSD(s)??? I know that SSD's are awesome at random read write speeds, but I dont know if a server is mostly doing random read writes or is more a sustained read write kinda animal? I have seen tests of this http://mac-fusion.com/blog/2009/12/11/mac_mini_server_raid_0_vs_raid_1_vs_other_macs/

Obviously R0 would be beneficial for sustained sequential reading writing; for randoms....not so much, but it would be easy to do and there is no real drawback other than some downtime if one of the drives goes

 

[talmy]

The more the clients the more the accessing will be random rather than sequential. (Imaging a dozen clients each reading a different large file at the same time -- the drive will be thrashing like crazy!) Distributing data over multiple drives and having lots of RAM for caching (hopefully data will be in cache) will help.

 

[Nanker/Phelge]

Yes, ZRD, am thinking of that as well. Since the boot drive will be backed up externally, why not, right? I started a new thread on possible upgrades andor mods that will improve file service performance and thats a good point to add. For instance, if I get a performance boost from R0, maybe SSD(s)??? I know that SSD's are awesome at random read write speeds, but I dont know if a server is mostly doing random read writes or is more a sustained read write kinda animal? I have seen tests of this http://mac-fusion.com/blog/2009/12/11/mac_mini_server_raid_0_vs_raid_1_vs_other_macs/

Obviously R0 would be beneficial for sustained sequential reading writing; for randoms....not so much, but it would be easy to do and there is no real drawback other than some downtime if one of the drives goes

I looked at the same results when I was considering this machine in December 2010, they look quote promising (at least for sequentials). Not sure how much external storage you'll be adding on but running them in RAID0 will also double the capacity of your boot disk.

 

[eprepguy]

yeah, therein lies the rub. I wont be using any boot drive space for storage of files, just booting and system access needs only. 1TB used to be a lot of space but we have single days here at the studio where we produce over a TB now. So all "real" storage will be handled by massive R5 arrays connected by either FW or possibly eSATA mod if necc. Right now its dispersed among 10 macs with multiple 1-3TB drives attached all over the studio. Thats why I am trying to consolidate to a centralized server; but I asked my employees if they want a multiprocessor killer massive UNIX beast server that would make all our work lives easier...or....pay raises and XMas bonuses? They mysteriously voted on pay raises and bonuses...go figure? So I must now figure out a sub $1000 system (actually could stretch a little if necc.) that will limp us along.