Intel 160 GB ssd drive now $425
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From: DevilsPGD on 7 Aug 2010 01:58 In message <S8ednUtsQ75G3MHRnZ2dnUVZ_sWdnZ2d(a)earthlink.com> "Timothy Daniels" <NoSpam(a)SpamMeKnot.biz> was claimed to have wrote: > That hybrid RAID system sounds intriguing (out of my league, but >still intriguing). Was all the software/firmware commonly available, >or did you author some of it yourself? Care to share pointers with >others here who might want to do the same or similar? Personally, I'm really looking forward to when some RAID card vendor grabs this idea and does it in hardware. Even better would be a controller built to support RAID-0 across several SSDs along with 1-2 HDDs for redundancy. I think you could probably have SSD write speeds too in most circumstances if you're willing to use the SSD as a buffer, and complete the write to the HDD as fast as that drive permits. There would obviously be some risk to data, but in order to have data loss you'd need to have an SSD failure mid-write and you'd only lose the amount of buffered data. You could still honour requests from the OS to flush the cache when needed. All of that being said, so far SSDs seem to have a level of reliability that exceeds traditional HDDs, so personally, I'm reasonably content with nightly images of my SSD, at least for most purposes.
From: Arno on 7 Aug 2010 13:42 Timothy Daniels <NoSpam(a)spammeknot.biz> wrote: > "Arno" wrote: >> Timothy Daniels wrote: >>> "Lynn McGuire" wrote: >>>> Intel 160 GB ssd drive now $425: >>>> http://www.newegg.com/Product/Product.aspx?Item=N82E16820167017 >>>> >>>> OK, this is getting very close to my buy point. Very close. >>>> >>>> Lynn >> >> >>> Hmmm.... Does anyone here know if SSDs can be RAIDed at level 0, >>> i.e. data striped for faster throughput? Would it make any sense to do so? >> >> Yes. But they require special controllers or suitable software RAID >> for this to make sense. Ordinary RAID controllers were designed with >> relatively slow access times and will often perform badly with SSDs. >> >> However, if throughput is your goal, conventional HDDs may perform >> similar, at a fraction of the cost. >> >> Incidentially, I have a HDD/SSD RAID1 running under Linux software >> RAID, with the HDDs set to be typically only written. Gives SSD >> read speeds in practive and HDD write speeds. Perfect for my >> application and even better than different brand HDDs in a RAID1 >> for added reliability. >> >> Arno > That hybrid RAID system sounds intriguing (out of my league, but > still intriguing). Was all the software/firmware commonly available, > or did you author some of it yourself? Care to share pointers with > others here who might want to do the same or similar? Very simple: Do a Linux software RAID1 and set the --write-mostly command line option when adding the HDDs/HDD partitions with mdadm. Add the SSD/SSD patition without that option. If doing this for an existing RAID, you will have to kick the elements one at a time, re-add with --write-mostly and wait for the RAID to sync. I did the latter, as I replaced one HDD partition in a 3-way RAID1 with an SSD. The software is just standard Linux kernel RAID via the md driver and the standard mdadm administration software. Nothing special at all needed. What you get is that reads go almost exclusively to the SSD, writes go to all (on RAID1). The option was originally intended when using a remote mirror, e.g. with ATA over ethernet, to reduce network traffic. All operations that need to read from the HDDs as well (e.g. consistency checks) will still do so. The RAID software just avoids reading from the member disks/partitions flagged as "write mostly" whenever it has a choice. Arno -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno(a)wagner.name GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
From: Timothy Daniels on 7 Aug 2010 23:00 "Arno" wrote: > Timothy Daniels wrote: >> "Arno" wrote: >>> Timothy Daniels wrote: >>>> "Lynn McGuire" wrote: >>>>> Intel 160 GB ssd drive now $425: >>>>> http://www.newegg.com/Product/Product.aspx?Item=N82E16820167017 >>>>> >>>>> OK, this is getting very close to my buy point. Very close. >>>>> >>>>> Lynn >>> >>> >>>> Hmmm.... Does anyone here know if SSDs can be RAIDed at level 0, >>>> i.e. data striped for faster throughput? Would it make any sense to do so? >>> >>> Yes. But they require special controllers or suitable software RAID >>> for this to make sense. Ordinary RAID controllers were designed with >>> relatively slow access times and will often perform badly with SSDs. >>> >>> However, if throughput is your goal, conventional HDDs may perform >>> similar, at a fraction of the cost. >>> >>> Incidentially, I have a HDD/SSD RAID1 running under Linux software >>> RAID, with the HDDs set to be typically only written. Gives SSD >>> read speeds in practive and HDD write speeds. Perfect for my >>> application and even better than different brand HDDs in a RAID1 >>> for added reliability. >>> >>> Arno > >> That hybrid RAID system sounds intriguing (out of my league, but >> still intriguing). Was all the software/firmware commonly available, >> or did you author some of it yourself? Care to share pointers with >> others here who might want to do the same or similar? > > Very simple: Do a Linux software RAID1 and set the --write-mostly > command line option when adding the HDDs/HDD partitions with mdadm. > Add the SSD/SSD patition without that option. If doing this for an > existing RAID, you will have to kick the elements one at a time, > re-add with --write-mostly and wait for the RAID to sync. I > did the latter, as I replaced one HDD partition in a 3-way > RAID1 with an SSD. > > The software is just standard Linux kernel RAID via the md driver > and the standard mdadm administration software. Nothing special > at all needed. > > What you get is that reads go almost exclusively to the SSD, > writes go to all (on RAID1). The option was originally intended > when using a remote mirror, e.g. with ATA over ethernet, to > reduce network traffic. All operations that need to read from > the HDDs as well (e.g. consistency checks) will still do so. The > RAID software just avoids reading from the member disks/partitions > flagged as "write mostly" whenever it has a choice. > > Arno > -- Thanks for the description. It makes sense. *TimDaniels*
From: Lynn McGuire on 8 Aug 2010 00:21 > That hybrid RAID system sounds intriguing (out of my league, but > still intriguing). Was all the software/firmware commonly available, > or did you author some of it yourself? Care to share pointers with > others here who might want to do the same or similar? Also see this new Seagate hybrid hard drive: http://www.newegg.com/Product/Product.aspx?Item=N82E16822148591 Lynn
From: Timothy Daniels on 8 Aug 2010 17:34
"Lynn McGuire" wrote: >> That hybrid RAID system sounds intriguing (out of my league, but >> still intriguing). Was all the software/firmware commonly available, >> or did you author some of it yourself? Care to share pointers with >> others here who might want to do the same or similar? > > Also see this new Seagate hybrid hard drive: > http://www.newegg.com/Product/Product.aspx?Item=N82E16822148591 Seagate Momentus XT ST95005620AS 500GB 7200 RPM 32MB Cache 2.5" SATA 3.0Gb/s with NCQ Solid State Hybrid Drive for $135 plus applicable state tax plus $6.30 shipping. Nice price point. *TimDaniels* |