Mycroft Holmes is a man who masters science, art and technology. He sees a world through the lenses of the Sony V1 and his Sony α.
Sunday, May 22, 2011
Saturday, May 21, 2011
Hybrid RAID
Digital photography needs a lot of storage.
A typical RAW file is about 1MB per megapixel, or more, so 100 pictures taken with a 16 megapixel camera may need 1.6 GB, which is usually to be multiplied by a constant factor because most programs will cache on the disk every kind of preview.
Adobe Lightroom needs 1 or 2 GB for CameraRaw output, plus it stores all the previews (standard and 1:1).
So it makes sense to have a very large drive for the pictures, and a very fast drive for the cache, but I'd really like to combine them in a single device.
There are some controllers that combine one small SSD drive and one large traditional drive, where the former is just a cache for the second, for example Silverstone HDDBOOST
With Silverstone card, the final capacity of the device is that of the magnetic drive, and the SSD transparently vanishes.
I was hoping that Adaptec Hybrid RAID solution would be a more complete solution, but it is not.
A hybrid RAID is simply a RAID 1 where one of the disks is a SSD; all reads are redirected to the SSD, while writes are replicated on both disks.
But the final size of a hybrid volume is the smaller of the sizes of SSD and the other drive, so it's just standard redundancy.
What is needed is actually Adaptec MaxIQ; this combines any number of traditional drives in whatever RAID and one or more SSDs, but it is also seriously expensive; you need either
- a special Q series Adaptec controller and a certified SSD (typically an enterprise-grade, so same performance as a corresponding consumer model, but not exactly cheap)
- a standard 2xxx or 5xxx Adaptec controller and Adaptec Max Cache, which is just a modified 32GB Intel X25 (now obsolete), sold at a monster price.
Walimex 500mm F/6.3
Walimex rebrands Samyang optics and sells them in Switzerland at a reasonable price.
After a very good experience with the Samyang fisheye lens, I recently decided to try another one, disregarding some negative comments I found. Anyway there are not many serious reviews of this lens.
http://www.walimex.ch/product_
After creating an account, I selected "payment form shipped along the items" (which is common in Switzerland), I placed the order and I immediately got a confirmation message, so it looked like everything went smoothly; after about one week, nothing had happened, I wrote them an email and I was told that my shipping address was unverified (?), so they wouldn't ship.
I simply offered to pay the lens in advance (which they consider equivalent to a verified shipping address...) and I got the package in 2-3 days.
The box contains the lens, a bag and a T2 ring adapter, which you have to tweak with a tiny screwdriver. If you mount the lens as is, it may be arbitrarily rotated with respect to the camera body, so in particular the distance scale meter may point downward.
The lens is a manual reflex tele, it has a mirror inside, so it's very short and wide; it has a limited depth of field, and it's really difficult to take a picture in focus. With a tripod, and lots of patience, you can get some results; without a tripod, it's totally impossible.
However the lens is so cheap, that I consider it a welcome gadget anyway; it's not something that you will carry around for casual use.
Sony used to produce an autofocus 500mm F/8, which is still on sale even if I think it has been discontinued, but it costs 4 times as much as the Walimex.
After a very good experience with the Samyang fisheye lens, I recently decided to try another one, disregarding some negative comments I found. Anyway there are not many serious reviews of this lens.
http://www.walimex.ch/product_
After creating an account, I selected "payment form shipped along the items" (which is common in Switzerland), I placed the order and I immediately got a confirmation message, so it looked like everything went smoothly; after about one week, nothing had happened, I wrote them an email and I was told that my shipping address was unverified (?), so they wouldn't ship.
I simply offered to pay the lens in advance (which they consider equivalent to a verified shipping address...) and I got the package in 2-3 days.
The box contains the lens, a bag and a T2 ring adapter, which you have to tweak with a tiny screwdriver. If you mount the lens as is, it may be arbitrarily rotated with respect to the camera body, so in particular the distance scale meter may point downward.
The lens is a manual reflex tele, it has a mirror inside, so it's very short and wide; it has a limited depth of field, and it's really difficult to take a picture in focus. With a tripod, and lots of patience, you can get some results; without a tripod, it's totally impossible.
However the lens is so cheap, that I consider it a welcome gadget anyway; it's not something that you will carry around for casual use.
Sony used to produce an autofocus 500mm F/8, which is still on sale even if I think it has been discontinued, but it costs 4 times as much as the Walimex.
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