From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hubert Kario Subject: Re: SSD Optimizations Date: Thu, 11 Mar 2010 15:01:55 +0100 Message-ID: <201003111501.55663.hka@qbs.com.pl> References: <4B97F7CE.4030405@bobich.net> <20100311135909.a7acc23e.skraw@ithnet.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=utf-8 Cc: linux-btrfs@vger.kernel.org To: Gordan Bobic Return-path: In-Reply-To: List-ID: On Thursday 11 March 2010 14:20:23 Gordan Bobic wrote: > On Thu, 11 Mar 2010 13:59:09 +0100, Stephan von Krawczynski >=20 > wrote: > >> >> > > >On Wed, Mar 10, 2010 at 11:49 AM, Gordan Bobic > >> >> > > > > >> >> > > > > >> >> > > >wrote: > >> >> > > >>Are there options available comparable to ext2/ext3 to he= lp > >> > >> reduce > >> > >> >> > > >>wear and improve performance? > >> >> > > >> >> > With SSDs you don't have to worry about wear. > >> >> > >> >> Sorry, but you do have to worry about wear. I was able to destr= oy a > >> >> relatively > >> >> new SD card (2007 or early 2008) just by writing on the first 1= 0MiB > >> > >> over > >> > >> >> and > >> >> over again for two or three days. The end of the card still wor= ks > >> >> without > >> >> problems but about 10 sectors on the beginning give write error= s. > >> > > >> > Sorry, the topic was SSD, not SD. > >> > >> SD =3D=3D SSD with an SD interface. > > > > That really is quite a statement. You really talk of a few-bucks SD= card > > (like the one in my android handy) as an SSD comparable with Intel = XE >=20 > only with >=20 > > different interface? Come on, stay serious. The product is not only= made >=20 > of >=20 > > SLCs and some raw logic. >=20 > I am saying that there is no reason for the firmware in an SD card to= not > be as advanced. If the manufacturer has some advanced logic in their = SATA > SSD, I cannot see any valid engineering reason to not apply the same = logic > in a SD product. The _SD_standard_ states that the media has to implement wear-leveling. So any card with an SD logo implements it. As I stated previously, the algorithms used in SD cards may not be as a= dvanced=20 as those in top-of-the-line Intel SSDs, but I bet they don't differ by = much to=20 the ones used in cheapest SSD drives. Besides, why shouldn't we help the drive firmware by=20 - writing the data only in erase-block sizes - trying to write blocks that are smaller than the erase-block in a way= that=20 won't cross the erase-block boundary - using TRIM on deallocated parts of the drive This will not only increase the life of the SSD but also increase its=20 performance. >=20 > >> > Honestly I would just drop the idea of an SSD option simply beca= use >=20 > the >=20 > >> > vendors implement all kinds of neat strategies in their devices.= So >=20 > in >=20 > >> the > >> > >> > end you cannot really tell if the option does something construc= tive > >> > and not destructive in combination with a SSD controller. > >> > >> You can make an educated guess. For starters given that visible se= ctor > >> sizes are not equal to FS block sizes, it means that FS block size= s can > >> straddle erase block boundaries without the flash controller, no m= atter > >> how > >> fancy, being able to determine this. Thus, at the very least, alig= ning >=20 > FS >=20 > >> structures so that they do not straddle erase block boundaries is >=20 > useful >=20 > >> in > >> ALL cases. Thinking otherwise is just sticking your head in the sa= nd > >> because you cannot be bothered to think. > > > > And your guess is that intel engineers had no glue when designing t= he XE > > including its controller? You think they did not know what you and = me >=20 > know >=20 > > and > > therefore pray every day that some smart fs designer falls from hea= ven >=20 > and >=20 > > saves their product from dying in between? Really? >=20 > I am saying that there are problems that CANNOT be solved on the disk > firmware level. Some problems HAVE to be addressed higher up the stac= k. Exactly, you can't assume that the SSDs firmware understands any and al= l file=20 system layouts, especially if they are on fragmented LVM or other logic= al=20 volume manager partitions. --=20 Hubert Kario QBS - Quality Business Software 02-656 Warszawa, ul. Ksawer=C3=B3w 30/85 tel. +48 (22) 646-61-51, 646-74-24 www.qbs.com.pl System Zarz=C4=85dzania Jako=C5=9Bci=C4=85 zgodny z norm=C4=85 ISO 9001:2000 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html