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ryanbloom

@sbcglobal.net

[My Review] Simple Rackmount Raid Backup Solution

I have been searching for a good solution for a few of my clients that have a server rack and want a simple and easy to use mirror array to use for backups. I finally stumbled upon what I think is a very good fit for what I was looking for. It is the Desert Scientific Z-Drive Rackmount Chassis.

The Z-Drive is "is a a premium drive array in a slim 1U rackmount format. Two cartridge bays are resonantly mirrored to provide constant access to data at all times." (from their website).

What I like most about this piece of hardware is that it does not require any software to run. It is pretty much just plug and play. What I also find great is that it is all steel. I have purchased many of this simple raid arrays and they are very cheaply constructed with plastic and they can not handle many hot swaps of the drives. This array is very rugged.

The price is right on this chassis. The chassis itself runs $595 and the cartridges that are either 1/2/3TB range from $295-$395.

I am very happy with this product and I will definitely be installing it for all of my clients that have a need for this.

If you guys want to check it out, you can see more details at http://www.desertscientific.com


koitsu
Premium,MVM
join:2002-07-16
Mountain View, CA
kudos:23

2 edits

1 recommendation

Comments in passing, because the vendors' website does not do a good job of making this apparent:

1. The device operates purely in a mirroring / RAID-1 fashion. No other modes are supported.

2. Appears to be another product where you have to use hard disks purchased from the vendor themselves.

3. The interface methods offered (to a host PC) are USB 3.0 and eSATA.

4. The User Manual indicates that there is an amusing design flaw in their product, especially given that the product is advertised repeatedly with this phrase. Quoting manual:

quote:
Z-Drive displays two drives to the host instead of one

The Z-Drive is capable of creating and storing multiple array configurations. For example, if both member cartridges are removed from the chassis a new array may be configured with the same chassis. If the member cartridges of this new array are then removed and the original cartridges re-inserted, the Z-Drive will remember the original array and function as expected. At this point, the Z-Drive is storing two array configurations. If one member cartridge from each array is inserted into the chassis at the same time, the Z-Drive will not be able to determine which array the operator intended to access. To avoid damaging any data, the Z-Drive will simply report both arrays as active but diminished. Hence, two drives will be reported to the host operating system.

During normal operations, cartridges from different array sets should not be mixed. If a cartridge needs to be moved from one array to a different array, the cartridge should first be cleaned so the Z-Drive does not report the cartridge as a member of a different array. To clean a cartridge, all partition information on the cartridge must be removed. Different operating systems have a variety of procedures to accomplish the cleaning process.

For Microsoft Windows operating systems the cleaning procedures are part of the diskpart utility and notated here: »technet.microsoft.com/en-us/libr···10).aspx Please note, the cleaning process is destructive and will remove all data on the cartridge. If a cartridge needs to be cleaned, a chassis should first have all its member cartridges removed. A single cartridge can be inserted into the chassis and the cleaning procedures executed while the second slot on the chassis is empty.

I've bolded/underlined the amusing parts. A device like this should not internally (i.e. possibly in NVRAM, or a dedicated flash storage medium) ""retain"" information about previously-created arrays. The array information should be stored as metadata on the drives themselves. Meaning: there should never, ever be a case where this unit "has knowledge of two array configurations" -- from it's perspective it should be operating as if there's only 1 configuration (one array/volume) at all times.

The 2nd amusing part is the "all partition information must be removed" -- that's a sly way of saying "you need to write zeros to every LBA on the drive". Guess what that requires you do? Pull the drive out of the chassis, hook it up to a PC somewhere, and use software to zero it. Oh the irony.

To me, this is another black-box device where you are stuck experiencing vendor lock-in. This one is even weirder than the rest because they don't want to give you any details about the device. You don't know if it's actually hardware RAID with cache and so on, or if it's just "BIOS-level" RAID (my guess is that it's probably the latter, i.e. being done on the cheap; it's probably some Silicon Image IC).

Finally, the price is really not that impressive: chassis = US$595, 1TB disk = $295. $595 + ($295*2) = $1185 plus tax + S/H.

For significantly less than that, I can get a 4-disk Supermicro chassis (which supports SATA300, AHCI, and has a hot-swap backplane), use 1 drive for an OS of my choice, and have 3 disks for storage (e.g. 2-disk RAID-1 with a standby spare, or RAID-5 across 3 disks), also allowing me to choose whatever drive brand/model/capacity I want (1TB drive on the market right now = $91. Compare that to $295). I can interface with it using Ethernet (gigE), which means either NFS, CIFS/SMB, or even things like FTP (limiting speed factor in all those cases is going to be disk I/O speed, which is the same limiting factor on the Z-Drive product!).

I would love to see someone do a review of this product, opening it up and showing its innards and what ICs it uses and so on.

So as someone who ran a hosting organisation for 18 years and owned quite a bit of hardware, consider me not very impressed by this device, especially given the price.
--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.


norwegian
Premium
join:2005-02-15
Outback

The OP may correct me, but I'd almost call this one spam.

I did enjoy your comments, and they may help others looking for a similar piece of hardware for them selves.
Function and costs are important things.
--
The only thing necessary for the triumph of evil is for good men to do nothing - Edmund Burke