NASLite Network Attached Storage

Can you set up a standard PCI IDE controller, lets use 2 x 300 GB Disks in this example, in Naslite for Disk-1 to mirror Disk - 0? or would my best bet be to use hardware RAID level 1?

My reason for asking is that a friend of mine wants me to build a NAS for him but wants to go as inexpensive as possible.

Thanks

Hi,

The difference between Mirror and Raid 1 is the frequency of the "update" of the copy.

In RAID 1, both disks are always the same all the time and if one fails, the data on the second is used instantly. But, if you DEL a file by error, it is gone from both disks.

In Mirror: the mirror copy is done at a given time. It is like a backup of the main disk. If the the main disk dies, you get your back-up disk wich will be up to date till the last mirror time (max 24 hours old). You have to set it up manually and use it. All new data since the last mirror will be lost. OTOH, if you DEL a file by error, it will still be on the mirror disk (till the next mirror time of course).

I hope this is clear enough.

Regards.

Thanks Robrub! it wasn't really the answer to my question but it helped my decision. I will go with the hardware RAID 1 set up for a continuous backup. Since this will only require a 2ch RAID Controller the cost won't be too high about $135 USD.

Actually - RAID1 and mirroring are one and the same thing - it is only with NASLite and on this forum that you will find disk mirroring used to refer to what is best described as "scheduled synchronisation."

Here's what Wikipedia has to say



Please note the phrase "in real time" - if it's not done in real time, which I believe is how NASLite does it - it's not mirroring, and if the primary disk fails before the next scheduled synchronisation occurs, any data written since the last synchronisation occurs will be lost.

By the way, I notice you say you're going to use RAID1 "for a continuous backup". RAID1 is not a form of backup - as robrub pointed out if a files is deleted, it's deleted from both disks, similarly any file corruption cause by a virus or whatever reason, will affect both disks.

so your saying that naslite running hardware raid 1 does not run in real time? why would that be?

No he is saying the disk mirroring feature of NASLite is not the same as RAID 1. Hardware RAID 1 (this is not affected by NASLite whatsoever since its all handled in the raid hardware) means the same data is written to two disks (arrays) at the same time (in real time) whereas the disk mirroring feature of NASLite is simply a way of copying data from one drive to another at a scheduled time. The point is, the disk mirroring feature of NASLite is not a substitution for a hardware RAID 1. Hope that makes it a little more clear

I guess I shouldn't have used the term backup as I meant redundant. looking for a failsafe in the event of a catastrphic hd failure.

thanks SB I thought that was the case.

The Naslite mirror option is pretty handy actually. I consider it a hybrid between RAID and a backup. It delays the replication of the data by 24 hours which means that in the event of main drive failure you will loose up to 24 hours of data. It does however give you a 24 delayed backup of the data in the event of deletions, corruption or any other user caused damage to the original data. The few places I've installed such setup love it and prefer to use it over incremental backup or RAID.

It's a very inexpensive and dependable solution if it fits your needs.

ok so if I use the mirror in naslite can I use a LSI megaraid sata 150-2 (fakeraid) controller if I am not doing raid?

I have bid on one on ebay then realized it wasn't hardware raid.

update:
I found some info at http://linuxmafia.com/faq/hardware/sata.html that indicated that the lsi megaraid 150-2 uses the Silicon Image 3112 driver. This driver is supported according to the naslite hardware reference guide. someone please correct me if I am incorrect.

The actual interface is supported but with no raid functionality.

Right....But I could still mirror disk-0 onto disk-1 correct?

If NASLite can see each drive then you can use the inbuilt periodic mirror function to mirror the contents of disk-0 to disk-1. When I did this (before hardware RAID) I set disk-1 to RO.