PDA

View Full Version : nas / sparseimage questions


postjosh
05-30-2006, 08:46 AM
hi. i'm planning on buying a Linksys NSLU2 network attached storage device for use with superduper. i'm aware that you must use the sparseimage format if you are planning on backing up accross a network. my questions are:

is there any reason to buy a larger drive for the nas than is needed to create the image of the drive that will be the source of the backup? i seem to remember from earlier superduper versions that while processing the program requires additional drive space to create the image.

as i know the initial backup accross the network is very slow, i was wondering if i could attach the target drive directly to the source computer via usb for the first backup. after that, i would put it on the nas for the "smart backup" updates. is that possible?

sorry if this is covered in the faqs. i didn't see it. thanks.

- josh

dnanian
05-30-2006, 09:24 AM
We don't need (much) extra space to create a sparse image -- only the regular overhead the system needs. But, your NSLU2 is going to need to be formatted as ext3 or something that will accept large single files, and doing so will preclude it being attached via USB (since it won't natively support HFS+, as far as I know).

You should definitely apply the most recent firmware update, too, and mount via SMB, since its AFP support is old, and doesn't support file addressing > 2GB.

Hope that helps!

DarkskyZ
05-30-2006, 04:37 PM
Hi,
I have just bought SuperDuper! yesterday and I am using a NSLU2. In fact my goal is to store my backups on it as anybody would use a NAS for...

My NLSU2 is upgraded to the unofficial uNSLUng firmware (http://www.nslu2-linux.org/) which actually brings many enhancements but the default filesystem is ext3 even with stock firmware. The NSLU2 is somehow slow but it is yet usable and very affordable.

You must just be aware that it is 10/100 MBps only, no Gigabit so huge amount of data can take ages to push or be pulled.

Your option of 1st backup using the drive attached to your Mac through USB is not possible as the drive HAS to be formatted ext3 to work on the NSLU2 and you Mac won't read or write it reliably as far as I know.

Hope that helps.

DarkskyZ

ScottEllsworth
05-30-2006, 08:38 PM
Out of curiosity, how slow is it? My TeraStation, direct on gigabit, gets about 1.5-2MB/s on Raid-5 for the initial write.

It gets far better, of course, when doing an update - up to 80MB/s - as reads for a terastation are far, far faster than writes. According to buffalo, even on gigabit, you are lucky to break 8 MB/s, and are usually closer to 5.

Scott

postjosh
05-30-2006, 10:35 PM
thanks for the tip about unslung. looks like the latest version will even allow ntfs disks.

postjosh
05-30-2006, 10:37 PM
dave, thanks for your help. i'll definitely heed your warning about samba.

- josh

DarkskyZ
05-31-2006, 11:07 AM
Out of curiosity, how slow is it? My TeraStation, direct on gigabit, gets about 1.5-2MB/s on Raid-5 for the initial write.
Scott
Well after a few tries I can tell you that it painfully reaches 1.4 MB/s using latest uNSLUng and matching up to date Samba. (tech details : iMac Core Duo GHz / 2GB RAM / 500GB Sata II linked to the 100 MBps NSLU2 by an ASUS WL500G Deluxe running DD-WRT)

The smart update speed means absolutely nothing as it fully depends on the amount of files you have changed on the source and their size.

I really thought the TeraStation would be really faster, I even considered trading my SLUG for one one them. I won't now... :rolleyes:

DarkskyZ => currently backing up 70GB to his NSLU2 with SD :D

dnanian
05-31-2006, 11:12 AM
One small tip for you guys: the underlying OS's handling of sparse images can cause slowness when the image is expanding -- something it does a lot of during the initial backup.

What you might want to consider, if you can afford the space, is using a read/write non-sparse image.

Once you've got one created on the NAS, you can mount it, and point SD! to its volume (not the file). We'll back up to that, and you'll see better speed.

We don't automatically unmount this type of image, but we will mount it. (You *might* be able to trick us into mounting/unmounting by giving it a .sparseimage extension, assuming that the OS will handle it right and not assume its structure based on the extension.)

Hope that helps!

DarkskyZ
05-31-2006, 11:46 AM
Thanks for the tip :)

Unfortunately, for space and management reason I can't use such an image with predetermined size. I will have to see how the smart update handles my 70GB on the sparse image though...

dnanian
05-31-2006, 11:48 AM
Fair enough. Just wanted to give the option.

ScottEllsworth
05-31-2006, 05:35 PM
Well after a few tries I can tell you that it painfully reaches 1.4 MB/s using latest uNSLUng and matching up to date Samba. (tech details : iMac Core Duo GHz / 2GB RAM / 500GB Sata II linked to the 100 MBps NSLU2 by an ASUS WL500G Deluxe running DD-WRT)

The smart update speed means absolutely nothing as it fully depends on the amount of files you have changed on the source and their size.

I really thought the TeraStation would be really faster, I even considered trading my SLUG for one one them. I won't now... :rolleyes:


Check out Tom's Hardware. He has reviewed a number of Raid5 NAS units, most of which outperform the Terastation. The terastations hideous speed is because of a design boo-boo. They are doing part of RAID-5 in software, so it is writing sequentially rather than in parallel. There are fixes, but the TS firmware does not use them.

Scott

postjosh
08-09-2006, 09:44 PM
One small tip for you guys: the underlying OS's handling of sparse images can cause slowness when the image is expanding -- something it does a lot of during the initial backup.

What you might want to consider, if you can afford the space, is using a read/write non-sparse image.

i'm not sure i'm following this. how can i create a non-sparse image? the only options sd gives me are sparseimage read/write and read only images.

also, i bought the nslu2 and i've formatted an external drive as ext3. i'm mounting it through samba and trying to use sd to create a sparse image on it. i keep getting error messages and no disk image is created. here's what the log says:

| 09:32:32 PM | Info | SuperDuper!, 2.1.3 (80), path: /Applications/superduper /SuperDuper!.app, Mac OS 10.3.9 build 7W98 (ppc)
| 09:32:32 PM | Info | Started on Wed, Aug 9, 2006 at 9:32 PM
| 09:32:32 PM | Info | Source Drive: wooriegi, mount: /, device: ST960822A, interconnect: Internal ATA, file system: "Journaled HFS+", OS: 10.3.9 (7W98), capacity: 55.76 GB, used: 47.71 GB, directories: 57359, files: 264455, ejectable: NO, ACLs: Disabled
| 09:32:32 PM | Info | Target Image: /Volumes/WORKGROUP;LINKSYS_NSLU2/wooriegi_backup.sparseimage, name: wooriegi_backup
| 09:32:32 PM | Info | Copy Mode : Erase, then copy files
| 09:32:32 PM | Info | Copy Script : Backup - all files.dset
| 09:32:32 PM | Info | Transcript : BuildTranscript.plist
| 09:32:33 PM | Info | PHASE: 1. Prepare to Copy Files
| 09:32:33 PM | Info | ...ACTION: Preparing wooriegi
| 09:32:33 PM | Info | ......COMMAND => Verifying the integrity of volinfo.database
| 09:32:33 PM | Info |
volinfo.database OK
| 09:32:33 PM | Info | ......COMMAND => Enabling permissions on wooriegi
| 09:32:33 PM | Info | Refreshing Disk Arbitration ...
| 09:32:33 PM | Info | ......COMMAND => Verifying that permissions are enabled for wooriegi
| 09:32:33 PM | Info | Permissions on '/' are enabled.
| 09:32:33 PM | Info | ...ACTION: Mounting wooriegi_backup
| 09:32:33 PM | Info | ......COMMAND => Preparing wooriegi_backup
| 09:32:34 PM | Info | Initializing...
| 09:32:34 PM | Info | Creating...
| 09:32:34 PM | Info | Finishing...hdiutil: create failed - Invalid argument
| 09:32:34 PM | Error | ****FAILED****: result=256 errno=0 (Unknown error: 0)


what am i doing wrong? thanks.

- josh

dnanian
08-10-2006, 01:35 AM
Actually, you're not doing anything wrong. This is a known problem in SD! with 10.3.x that we'll be fixing in the next release. In the meantime, the workaround is to create the sparse image, of the appropriate size, using Disk Utility. You'll only have to do this once.

1. Open Disk Utility (found in /Applications/Utilities).
2. Without selecting any volume/drive on the left side, click the New Image toolbar button.
3. Give the image an appropriate name (like Backup), and store it on a drive other than the one you're trying to back up.
4. In the Size pop-up, choose Custom.
5. In the sheet that appears, enter the size of the drive you're trying to back up. Note that the pop-up does not have a selection for GB: you need to enter "40000" MB for 40GB. Click OK when you've got the right size entered.
6. Decide whether or not you want the image encrypted, and choose the proper value in the Encryption pop-up.
7. In the Format pop-up, choose sparse disk image. Or, if you want a "regular" read-write image, choose that. Note that if you choose a regular (non-sparse) image, you need to point us to the volume that's created, not the file.
8. Click Create.

Once it's created, go back to SuperDuper! and choose the "Disk Image..." selection in the destination pop-up (unless you're using a regular image). Navigate to the location where you created the image and click it (it's grey, but that's OK -- click it anyway), then click "Save".

Hope that makes some sense, Josh...

postjosh
08-12-2006, 08:36 PM
worked great! here's my setup:

ibook g4 with an airport card running panther
linksys nslu2 nas running unslung 6.8 beta firmware
my network has the nslu2 connected via ethernet to an airport extreme connected wirelessly to a second airport extreme via wds
i mount the nslu2's western digital drives via samba

since i have plenty of drive space, i opted to create a "dmg" image using disk utility on the nslu2. this worked well, but it took a LONG time. about 10 hours to do a 56GB image. i then used superduper which ran at about 1.09 mb/sec which also took overnight, but that's fine for the initial backup.

the main thing is nothing became unmounted or crashed! i also ran a smart backup just to see how it would work. i have two drives on the nslu2. one is for itunes, etc. and the other is for backup. the itunes drive is normally connected to the g4, so that means that the nslu2 is always logged in. i was VERY HAPPY to see that super duper was able automatically mount the backup drive and dmg image and backup without any intervention from me. this means i should be able to schedule my backups automatically in the future.

thanks, dave. sd rocks and your support is outstanding!

- josh

dnanian
08-13-2006, 10:23 AM
Thanks, Josh. I'm glad that all worked as expected -- or better! :)